Junior High School English Olympiad Sample Question 20, this is a junior high school English Olympia

Purple: Poisonous if and only if the red mushroom is poisonous.

Yellow: 6 months of the year are toxic.

Green: Purple mushrooms can be safely eaten if and only if they are poisonous.

Red: Safe for 6 months of the year.

Based on the above conditions alone, I consulted many experts in the classification of educational science, but they couldn't deduce anything, lack of conditions, upstairs said that you can eat green now, but how do you analyze that the purple and red are poisonous now?

There must be other conditions or restrictions, otherwise nothing can be inferred in this way.

Always and only and only always mean the same thing, and the translation can be said to be and only if.

For example, always and only poisonous if the red mushrooms are

Meaning, purple mushrooms are always poisonous when red mushrooms are poisonous, and purple mushrooms are poisonous only if they are poisonous when red mushrooms are poisonous, that is, if and only if.

According to the reverse reasoning you mentioned, I guess there is only this answer, but I think that if this is the answer, the question should be if there is only one kind of mushroom to eat, which one? Because the green one may also be poisonous, it can only be established if only one kind of mushroom is known to be edible, and it does not mean that the green one is not poisonous, and if it is not stated in the title, it can only be assumed in this way, then the answer should be a green mushroom.

Complaining, the current topic, what do you mean by this kind of topic? It's destroying the flowers ... Let's learn reasoning, the proposition is not rigorous, let's learn English, there is no English value at all, alas.

Purple bar.

Because she said that it was only poisonous when it was red, and now it is purple, it is not poisonous.

Now you can eat the green ones.

Because red is poisonous when purple is also poisonous, neither red nor purple can be eaten. Yellow is not exact.

And green can be eaten when purple (and red at the same time) is poisonous.

So green can be eaten.

x=1, y=2, z =3

a borrow from. Borrow, he should borrow money from his mother lent to have yesterday in the past tense.

And Mothe is a mother, right?

1、x=1,y=2,z=3

3. a, because the borrow ...... is from ......borrowed.

Sentences should be in the past tense.

1.IT refers to a person whose gender is unclear or uncertain.

2.It as a formal object refers to to climb hills

It is done as a formal object instead of the subject that follows.

The two questions are one meaning.