Scientists say it may be five or six years __________it is possible to test this medicine on human patients.
| A．since | B．after | C．before | D．when |
I don’t think she has to do so, ___?
| A．has she | B．do I | C．does she | D．have I |
Facing danger, he always ___ calm.
| A．turns | B．seems | C．remains | D．appears |
The nurse worked hard to help the sick and ___ .
| A．the dead | B．the dying | C．the dead man | D．the dying man |
Watch the man ___ it. And you should do ti in the same way.
| A．do | B．to do | C．doing | D．done |
I wish I ___ to the football match last night.
| A．went | B．would go | C．had gone | D．had been |