The boss insisted that every minute ______ made full use of ______ the work well.
| A．be, to do | B．was, doing |
| C．be, doing | D．was, to do |
You will find friendly people ___ you go in China.
| A．where | B．and | C．wherever | D．so |
He lay ___ the grass was the thickest.
| A．where | B．when | C．that | D．after |
Go back ___ you came from.
| A．until | B．where | C．which | D．when |
The doctor will not perform the operation ___ it is absolutely necessary.
| A．when | B．if | C．for | D．unless |
Difficulties are nothing ___ we are not afraid of them.
| A．for | B．as | C．if | D．whether |