It never occurred to humans until the mid-1990s ______ some animals can be cloned.
| A．where | B．that | C．when | D．what |
He’s got himself into a dangerous situation ___he is likely to lose control over the plane.
A. whereB whichC. while D. why
The fact is ______ he has not been seen recently.
| A．what | B．that | C．why | D．if |
Mrs White found her husband ________by letters and papers and________ very worried.
| A．surrounding ; looked | B．surrounded ; looked |
| C．surrounding; looking | D．surrounded ; looking |
He told ______ should read.
| A．me what I | B．me I what | C．what me I | D．what I me |
There was plenty of time. She ______ .
| A．mustn’t have hurried | B．couldn’t have hurried | C．must not hurry | D．needn’t have hurried. |