.Nobody noticed the thief slip into the house because the lights happened to_____.
| A．be put up | B．give in | C．be turned on | D．go out |
The school _______ I visited the other day was not the one _______ I once studied.
| A．that; which | B．which; where | C．where; which | D．where; where |
Is this the reason____ at the meeting for his carelessness in his work?
| A．he explained | B．what he explained |
| C．how he explained | D．why he explained |
You stepped into the lab with your shoes on? You’re _______ to take them off before you enter it.
| A．invited | B．supposed | C．forbidden | D．permitted |
—We could invite John and Barbara to the Friday night party.
—Yes, ______ ? I’ll give them a call right now.
| A．why not | B．what for | C．why | D．what |
Jack wasn’t saying anything, but the teacher smiled at him _______he had done something very clever.
| A．as if | B．now that | C．while | D．though |