1 . Some young people these days just ______ go out of their homes to contact the real world．

A．mustn’t

B．won’t

C．mightn’t

D．shouldn’t

2 . Every solid object ______ reflect a sound，varying according to the size and nature of the object．

A．must

B．shall

C．will

D．should

3 . .
If you ________ be quiet, I will tell you what happened.

A．will

B．may

C．shall

D．must

4 . —Why does Thomas speak through every discussion but never listen to the others?
—That's what he ________ do. We used to hate that, but are used to it now.

A．ought to	B．can
C．will	D．might