People in the west make_______ a rule to buy Christmas presents for their relatives and friends.
| A．it | B．that | C．this | D．as |
（2012江西卷）It suddenly occurred to him he had left his keys in the office.
| A．whether | B．where | C．which | D．that |
As many five courses are provided, and you are free to choose ______ suits you best.
| A．whatever | B．whichever | C．whenever | D．wherever |
Scientists study ____ human brains work to make computers.
| A．when | B．how | C．that | D．whether |
（2012辽宁卷）The newcomer went to the library the other day and scarched for he could find about Mark Twain.
| A． wherever | B． however | C．whatever | D．whichever |
_____ I want to tell you is the deep love and respect I have for my parents.
| A．That | B．Which | C．Whether | D．What |