________he can't understand is ________his son doesn't like the school.He is very upset about this.
| A．That；why | B．Why；that |
| C．What；why | D．Whether；that |
The ___________ boy was last seen ___________ near the East Lake.
| A．missing ； playing |
| B．missing ； play |
| C．missed;played |
| D．missed;to play |
It was never clear ___________ the man hadn't reported the accident sooner.
| A．that |
| B．how |
| C．when |
| D．why |
It is uncertain ___________ side effect the medicine will bring about，although about two thousand patients have taken it.
| A．that |
| B．what |
| C．how |
| D．whether |
It never occurred to me ___________ you could succeed in persuading him to change his mind.
| A．which |
| B．what |
| C．that |
| D．if |
The football match was said ___________ in Rome last week.
| A．to have been held |
| B．to be holding |
| C．to hold |
| D．to have held |