--- Walking an hour every day is good for our health.
--- Exactly. However, ________.
| A．I love doing it very much. | B．I don’t hate it. |
| C．Climbing a mountain is also good. | D．I don’t like to do it every day. |
___ it was already dark, they went on working in the fields.
| A．If | B．Whether | C．But | D．Though |
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 |