Can you tell me why English experts can help me with multiple-choice questions?

Reason: follow the rule of sufficiency (adj+ sufficiency/sufficiency+n.), and exclude B and D first.

According to the meaning of the sentence, you can do it yourself, so choosing A is simple enough.

2.c

Reason: obey the rules: someone takes time to do something.

So collect-collect, choose C.

3.c

Reason: according to the general present tense, exclude D first.

Follow the rules: someone spends time on something, so choose C.

4.a

Reason: The English of 1 10 is 110, so the article uses A, excluding C and D.

In the sentence, 1 10 is a long adjective with a "-"in the middle, so choose a.

5.d

Reason: v+n and house appeared in front, so they were used to buy, excluding a and C.

Because too ... to ... is a fixed match, choose D.

6.a

Reason: Here is the formal object. This sentence pattern is "think someone does something".

So choose one

7.c

Reason: be verb is, so it is simple present tense.

Yesterday was the past perfect tense, a few days later was the general future tense, and those days were the general past tense.

Only C (these days) is the simple present tense, so C is chosen.

8.c

Reason: fixed phrases collocation: encourage someone to do something.

Participate in+activities

So choose C.

9.b

Reason: be verb is are and plural. Let's exclude C and D first.

Because it means both sides of the street, it is B (both sides).