问题

________scores of times, but Derek still couldn’t understand how to use past participle in a concrete situation

A:Having explained
B:Having been explained
C:Though it was explained
D:It was explained

正确答案是：

同类题型

___ read your letter when the bell rang.

I was told that there were about 50 foreign students _______ Chinese in the school, most_______ were from Germany.

______ and you will be admitted into your desired university

Nowhere else in the world ________ such a quiet，beautiful place.

My parents _____eat junk food, because it’s bad for our health.