问题

The split between humans and living apes is thought by some scholars ____ 15 to 20 million years ago.[ ]
A: to occur
B: occurring
C: to have occurred
D: having occurred
B: occurring
C: to have occurred
D: having occurred
正确答案是:
同类题型
The tomato juice left brown ____ on thefront f my jacket
I can’t believe that anyone else in the school can swim as fast as you, ?
We must read between the lines, and sometimes _____ the lines, to fully understand the writer.[ ]
How I wish I _____ have a long holiday, doing things that I like. [ ]
My son is _____ to be seen Where has he gone — I think he _____ in the building