1.I really don't know where ---------- A.it is bought B it i

1.I really don't know where ---------- A.it is bought B it is bought C did he go D he went答案是D
2.My brother became interested in music -------?A until last year B at the age of eighteen C since five years D since three years ago 但是为什么C与D 不能选呢 还有since 后面跟的是什么 是一段时间还是 .
3.To plant the tree ,the __ must be neither too wet nor too dry ,and we must dig _____ .
A.floor ,athree-foot -deep hole
B ground a three feet deep hole
C floor a three-feet -deep hole
Dground a hole three feet deep
但是不知道为什么A B C 错在哪里