__________ you understand the rule, you will have no further difficulty.
| A．While | B．Once | C．Though | D．Unless |
. This sentence needs ___________ .
| A．a improvement | B．improve | C．improving | D．improved |
. ___________ anything about the accident, he went to work as usual..
| A．Not known | B．Known not | C．Knowing not | D．Not knowing |
. The next morning she found the man ___________ in bed, dead.
| A．lying | B．lie | C．lay | D．laying |
. There was terrible noise ___________ the sudden burst of light.
| A．followed | B．following | C．to be followed | D．being followed |
. The secretary worked late into the night, ___________ a long speech for the president.
| A．to prepare | B．preparing | C．prepared | D．was preparing |