______ carefully if any change occurs when doing experiments in the lab.
| A．Observe |
| B．To observe |
| C．Observed |
| D．Observing |
We'll have to find a job, ________.
| A．long it takes however |
| B．it takes however long |
| C．long however it takes |
| D．however long it takes |
This vase wasn't________properly before it was put away.
| A．wiped up |
| B．wiped over |
| C．wiped off |
| D．wiped out |
________the farmers were pleased the good harvest of this year.
| A．A great deal of |
| B．A great many |
| C．A great many of |
| D．A large amount of |
My father made me a promise________I got a good mark he would buy me a present.
| A．that |
| B．which |
| C．that if |
| D．if |
Instead of________， Hawing went on with his research, got his PhD and married the girl.
| A．giving in |
| B．giving out |
| C．giving away |
| D．giving up |