If it s a master, come and help me answer, and a scientific expert can help

I read the wrong serial number.。。。 The serial number is subject to the landlord's drawing).

The four periods of ABCD are marked on the map, when the earth is in the [D] position, China is about the winter solstice; When the earth is in c, we are about the time of the vernal equinox. When the Earth is in [d], there will be a polar night phenomenon in the area north of the Arctic Circle. When the earth rotates to [b], the daylight hours in China are the longest.

According to the diagram explaining the origin of the four seasons [related to the revolution, but the decisive condition is that the earth must revolve diagonally around the sun; If the earth rotates vertically around the sun, the sun's rays will always shine directly near the earth's equator, and the angle between the earth's plane and the sun's rays will never change, and there will be no change of seasons on the earth

The picture is not clear to see, so I had to change the picture, it seems to be about the same - =

c position, our country is about the winter solstice season. The winter solstice is on December 22 every year, when our country is in winter, and the sun shines directly on the Tropic of Capricorn.

The answer to the second question is the same as the first question (winter solstice, position c) There is a polar night phenomenon in the Arctic Circle.

a, the longest daylight hours in our country. The summer solstice is short, the winter solstice is long, the sun slowly moves north from the equator, that is, the spring equinox to the summer solstice, the daytime time in China is getting longer and longer, and when it reaches the summer solstice, that is, when the A position in the figure, the sun shines directly on the Tropic of Capricorn, and our country reaches the longest day of the day. The causes of the four seasons are formed by the rotation of the earth.

1、 ÷2 + 20%

2. Alloy weight before adding copper: 68 - 5 = 63 Total parts: 3 + 4 = 7

Weight of each serving: 63 7 = 9 kg

Weight of copper before addition: 9 3 = 27 kg Weight of pre-zinc added: 9 4 = 36 kg Weight of copper after addition:

27 + 5 = 32 kg of copper-zinc ratio for the new alloy: 32 : 36 = 8 : 9

1. From the title, it can be seen that the school plans to invest 10,000 yuan, but the actual investment is saved, so the actual investment is saved.

2. Because the mass of the new alloy is 68 kg, the mass of the original copper-zinc alloy is 63 kg. Therefore, in the original copper-zinc alloy, the mass of copper is 63 * (3 7) = 27kg, and the mass of zinc is 63 * (4 7) = 36kg, so the mass of copper in the new alloy is 27 + 5 = 32kg, so the ratio of copper and zinc in the new alloy is 32 36 = 8:9

1) 2) The weight of the original copper (68-5) * 3 7 = 27 The weight of the original zinc (68-5) * 4 7 = 36

The weight of copper later is 27 + 5 = 32

/(20%2.The quality of zinc is:

68-5）* 4/7=36kg

The quality of copper is.

68-36=32kg

The ratio is 36:32 = 9:8

For ideal components. Both capacitors and inductors are reactive power. That is, no power is lost, only energy is stored in inductors and capacitors.

Resistance is active power. For actual components, due to the existence of equivalent resistance, both capacitors and inductors will lose power, and the power is also positive. The negative value you are talking about is the calculated value that occurs in the circuit calculation due to the different direction of the current.

There is also a negative resistance in the theoretical calculations, and the calculated value may also be negative power.

1.The total power of the resistive element is positive, and the electrical energy is converted into heat energy, so the resistor generates heat.

The second point and the third point together, capacitors and inductors are energy storage components, the total power w 0, the current of the capacitor is ahead of the voltage of 90 °, the voltage of the inductor is ahead of the current of 90 ° (I don't know if you can see it), if the current power supply is a DC power supply, the moment the switch is just closed, although the capacitor and inductance show energy consumption, (in fact, it is energy storage), this part of the energy will be released at the moment when the switch is disconnected, so the total power of the capacitor and inductor is w 0

The main function of the standard resistor is to generate heat, and when connected in parallel with other components, the resistor can be shunted. When connected in series with other components, the resistor can be divided.

In addition, resistive elements include resistors made of semiconductor materials. Their resistance changes with the external conditions.

1. The resistance of the thermistor decreases with the increase of temperature. Connected to a circuit, the temperature in the circuit can be determined by its resistance value (thermal sensor).

2. The resistance of the photoresistor is greatly reduced when there is light. When connected to a circuit, it is equivalent to an "optical switch".

3. Crystal diode and transistor. Made in pure semiconductor materials, doped with specific trace amounts of magazines.

Sometimes, resistive elements are also referred to as superconductor elements. The application prospect of superconductor is mainly reflected in electronics, which should be that when it conducts electricity, it will not "generate heat", and it does not need a cooling system to make computer components, which can greatly reduce the volume and energy consumption of the computer.

Capacitance: A device consisting of electrodes made of two conductors that are close to each other and insulated from each other to store electrical charge and energy.

The role of inductance in a circuit.

Basic functions: filtering, oscillation, delay, notch, etc.

Figuratively speaking: "DC is passed, AC is blocked".

The power of resistive elements is not necessarily positive, and a few elements have negative resistance properties. Some devices (such as some tubes, transistors, diodes, etc.) have a decrease in voltage (or current) when the current (or voltage) increases under certain conditions.

The power of the capacitive element, the power is positive when charging, and the power is negative when discharging.

The power of the inductive element, the power is positive when charging and the power is negative when discharging.

As long as the resistance is connected to the circuit, that is, there is a current flowing, then the resistance will consume power, power is a physical quantity that describes how fast or slow the current does work, and here it has nothing to do with the direction of the current, so it is positive. Power is only available when connected to a closed loop.

1.The power of a resistive element is always positive. 2.The power of a capacitive element is always negative. 3.The power of the inductive element is always positive.

I don't know what kind of master you said.

The world is developing, the times are progressing, and people must also advance with the pace of the times.

If you have troubles, take 2 deep breaths first, and then think about the problem, and your mood will be much better.

Power is the amount of work done per unit of time, and it should be positive! So 1 and 3 pairs.

How to affirm yourself, first of all, you must have self-confidence, think that you can do anything, only realize that through your own efforts, you will be able to achieve your goals. Mentally confirm that you can do it, and cheer yourself up. As long as you are mentally prepared, you will not be held back by the slightest difficulty.

By believing in affirming your worth, you will be able to complete the task with confidence. The world is developing, the times are progressing, and people must also advance with the pace of the times.

You just have to think differently and you can come up with the answer for yourself:

Resistors always consume active power;

Capacitive inductors can both store energy and provide energy.

This person must have something important to do, and he can't do it without him, and after walking faster, you can feel for yourself how different it is from usual. Of course, you don't want to enjoy the scenery or go shopping with your girlfriend.

You may not even know the question yourself.

1.The power of a resistive element is always positive. Is that right? 2.The power of a capacitive element is always negative. Is that right? 3.The power of the inductive element is always positive. Is that right? Ask for an explanation!!

This kind of weather is still relatively faint, there is a professional ** The situation is being further investigated, I don't like to talk so late, talking like this doesn't represent the character, the reason why I want to go home is that he has lived a long, long life over there, many times it is very simple, what will happen in this situation, what is going on at home, I don't know why I am like this, I want to call him like this, what do you mean, so that I will feel that it is good that we are in the city of China.

You don't understand the world of adults, if your mother likes this kind of life, don't worry about it, don't call the police, lest your mother be hurt, you are a child to study hard, don't let adults worry about things, affect the future, the future, talk to your mother well, don't let him affect your mood.

Regardless of whether you have something to do, speeding up your own walking will give others a feeling that this person must have something important to do, and he can't do it without him, and after speeding up walking, you can feel it yourself.

Speed up the pace at which you can walk. Walking procrastination and laziness can give the impression of being idle and aimless. Regardless of whether you have something to do, speeding up your own walking will give others a feeling that this person must have something important to do, and he can't do it without him, and after speeding up walking, you can feel for yourself what is different from usual.

Of course, you don't want to enjoy the scenery or go shopping with your girlfriend.

6 taels plus 10 taels and 1 catty. This was the standard of ancient weighing.

In the past, the old scale was 16 taels for 1 catty. You can fill in: 6 taels + 10 taels 1 catty. I don't know if it's right?