问题

With the help of high technology, more and more new substances ______ in the past 10 years.

A:discovered
B:have discovered
C:had been discovered
D:have been discovered

正确答案是：

同类题型

下列句子中不包含通假字的一项是

Her father didn’t ask her to do it, but he didn’t ask her not to do it,______.

the poor grades, Maria is wondering whatit to learn English well.

Can you give me the right answer?—Sorry, I ______ Would you repeat that question?

－How iseverything going, Jack－________________