The boys were about to go out to play football suddenly it began to rain.
| A．when | B．as | C．while | D．then |
According to the school rules, no student __________ go out of the school after eleven o’clock at night without the teacher’s permission.
| A．will | B．must | C．may | D．shall |
Going on a trip into space must be quiteexciting experience.
| A．/ ; the | B．the; the | C．the; an | D．/ ; an |
Food supplies in the flood-stricken area _______. We must act immediately before there’s none left.
| A．have run out | B．have been run out | C．are running out | D．are being run out |
He _______ have taken your car by mistake because he didn’t have the keys.
| A．mustn’t | B．shouldn’t | C．couldn’t | D．needn’t |
It is not always easy for the public to see _______ use a new invention can be of to human life.
| A．whose | B．which | C．that | D．what |