Once he saw his daughter back safe, his ______disappeared.
| A．surprise | B．anxiety | C．imagination | D．curiosity |
To those scientists, it still remains to be a question ______ man can go back to the old days with time machine.
| A．if | B．that | C．how | D．whether |
There is a common belief among them _______ rubbish can and should be put into good use.
| A．which | B．if | C．whether | D．that |
We never doubt ______ our school team will win the match against No. 3 Middle School.
| A．whether | B．that | C．if | D．what |
The teacher usually grades the students on _______ they have behaved.
| A．that | B．what | C．which | D．how |
Once _____, it won’t be easily forgotten.
| A．saw | B．seeing | C．seen | D．see |