How long ______ we take part in the college entrance examination?
| A．is it since | B．will it be before | C．is it when | D．will it be since |
All Mrs Smith's efforts to tidy the room were _____ because her grandson soon made a mess of it again.
| A．at all costs | B．at random |
| C．in vain | D．in return |
___ is left over may be put into the refrigerator, ____ it will keep for two or three weeks.
| A．Whoever; when | B．Whenever; which |
| C．Whatever; where | D．Whichever; while |
Modern science has given clear evidence ____ smoking can lead to many diseases.
| A．what | B．which | C．that | D．where |
Three young men have been arrested because they were caught ___ an old lady last night.
| A．robbed | B．to rob | C．rob | D．robbing |
______ a little earlier, you could have got a copy of his latest book.
| A．If you would arrive | B．If you arrived |
| C．Should you arrive | D．Had you arrived |