问题补充:
By the time he was twelve he a chemistry lab of his own.
A. built
B. has built
C. had built
D. was building
答案:
A. built
B. has built
(答案→)C. had built
D. was building
解析:有by the time 引导的短语或从句,主句应该是完成时态,至于是什么完成时态,就看by短语或从句中的时态了。
时间:2020-02-07 05:29:05
By the time he was twelve he a chemistry lab of his own.
A. built
B. has built
C. had built
D. was building
A. built
B. has built
(答案→)C. had built
D. was building
解析:有by the time 引导的短语或从句,主句应该是完成时态,至于是什么完成时态,就看by短语或从句中的时态了。