________ in the regulations that you should not tell other people the password of your e-mail account.
| A．What is required |
| B．What requires |
| C．It is required |
| D．It requires |
My parents live in a small village. They always keep some candles in the house __________ there is a power off.
| A．if | B．unless |
| C．in case | D．so that |
We've worked out a method __________ our production can be greatly raised.
| A．with that | B．what |
| C．of which | D．with which |
Part of the reason Charles Dickens loved his own novel, David Copper field, was __________ it was rather closely modeled on his own life.
| A．what | B．that | C．why | D．whether |
It has been proved __________ eating vegetables in childhood helps to protect you against serious illnesses in later life.
| A．if | B．that | C．when | D．because |
The reason why he was sent to the hospital was __________ he was ill.
| A．that | B．because | C．since | D．why |