A few __________ looked at him curiously when he suddenly stopped and burst out crying.
| A．passers-by | B．passer-bys |
| C．passers-bys | D．passer-by |
We shall go ____ you are ready.
| A．while | B．as soon as | C．as | D．since |
Mark was a student at this university from 1999 to 2003, ____ , he studied very hard and was made Chairman of the Students' Union.
| A．during which time | B．for which time | C．during whose time | D．by that time |
It has not been decided ____ they will leave.
| A．why | B．when | C．which | D．what |
The accident is reported to have occurred __________ the first Sunday in February.
| A．at | B．on | C．in | D．to |
The trouble is ____ we can not find such an expert.
| A．why | B．that | C．where | D．/ |