We often think of the days ___we spent together on the island.
| A．when | B．which | C．in which | D．during which |
To learn to swim well, ___________.
| A．one needs much practice | B．much practice is needed |
| C．much practice needs | D．one is needed much practice |
The next thing he saw was smoke ______ from behind the house.
| A．rose | B．rising | C．to rise | D．risen |
They began to think about what use could be ______ such materials.
| A．made up | B．made from | C．made out | D．made of |
Tom ______ close the window when his attention was caught by a bird.
| A．was to | B．went | C．was about to | D．would |
He has made some spelling mistakes in the paper; ______, they are not serious.
| A．but | B．therefore | C．even if | D．however |