—How’s your new babysitter?
—We ______ ask for a better one. All of our kids love her so much.
| A．might | B．mustn’t | C．couldn’t | D．should |
The murder was brought in, with his hands ___ behind his back。
| A．being tied | B．having tied | C．to be tied | D．tied |
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 |