Question

Have they sent or Had they sent which is right
explain these two sentences when it is used​

Answer 1

Answer:

Had they sent

Explanation:

because sent is 2 form of send. so sent is used with past tense ............(with had)

Answer 2

Answer:

Both are right, but it depends on the situation where you're using it.

Have they sent their entries to the competition?

Had they sent their entries before the competition ended?

Sentence 1 is present perfect. It is used when something has been done in past but still has its effect. For example,

My uncle has completed his Masters. (he had completed it long ago but still holds the degree)

Sentence 2 is past perfect. It is used to tell about an action which occurred before a given point in the past. For example,

I had reached the station before the train arrived.

Here, before the train arrived is the given point and so the action which is done before this is expressed in past perfect.

Hope my answer helps.