Master, please help me explain, please answer carefully

Idiomatic habits in spoken American language.

Some denote past tense meanings, like she got married in1954

Some are colloquial habits, like the i you say've got quite a few tanks.

At this time, the GOT is dispensable, and after adding it, it also has the meaning of "I already have" in it.

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

The first question is okay as you think, but the Eiffel Tower should be designed, so it should be passive, that is, if you want to use the perfect tense, it should also be in the passive form of the present perfect tense, but it is not suitable in this question, because this question does not indicate the continuation of this action, mainly to emphasize the occurrence of the action design. be designed to do for what purpose. There is also the answer to this question is obviously wrong, the answer should be used in the past passive, it should be designed, you can look it up on the Internet, it should be the 2012 Beijing Haidian District mock question.

The second question is the present perfect continuous tense, which indicates the action that is being carried out before the moment of speaking, and this sentence means that I have been looking forward to Sally's ** for these two hours.

The third question, like the first one, wants to emphasize the action of discovery. Instead of wanting to emphasize the state of discovery, or the impact on the present, use the simple past tense.

These three questions illustrate a problem for you, you don't understand the difference between the present perfect tense and the usual past tense, and you can look at the grammar book again and ask the teacher when you have time.

1.is designed, which refers to the design requirements, not when the design will be completed.

Since odd function * even function = odd function, h(x) = f(x) g(x) is an odd function.

x<0 (f(x)g(x)).'=f '(x)g(x)+f(x)g '(x) > 0, so h(x) is a single increase function when x<0;

Since it is an odd function, h(x) is also a single increase function at x>0, and h(-3)=h(3)=0

So the solution set of f(x)g(x)<0 is (- 3) and (0,3).

Note: The odd function needs to satisfy h(0)=0, but this does not contradict h(-3)=0=h(0), because it may be a discontinuous piecewise function, increasing to a positive number at x<0, f(0)=0, starting from a negative number and increasing again at x>0, please imagine the image for yourself].

A. Food is an important exogenous factor affecting CD segment fluctuations.

The direct cause of CD fluctuations is changes in environmental factors.

In the process of this species, the proportion of AB larvae was greater than that of CD larvae.

1).Weight of rice taken out of bag A: 60*20%=30 kg.

Weight of rice taken out of bag B: 60*2 3=40 kg.

So a total of 70 kilograms of rice were taken out.

2).Question when the concentration is diluted for the first time? If yes.

Let the amount of water added for the first time be x and the multiplier is n

36%*x=

x = second dilution.

n = So the amount of water that needs to be added is twice the amount of water that needs to be added the first time (about equal) If not, just change it.

The lines of the two straight cherry sedan cars are parallel and the isotopic angles are equal, so angle 1 = angle EFD, and the sum of angle EFD and angle 3 is 180 degrees of ridge orange, so angle 1 + angle 3 = 180 degrees.

Very simple.

Each section is 1/5 of 8 meters;

8/5 of a metre long in each section;

Each segment is 2 meters of 8 5 2 = 8 10

Are you this won't you? It's not a difficult question.