Polar bears live mostly on______ sea ice, which they use as ______platform for hunting seals.
| A．a; a | B．a; the | C．不填; a | D．the; 不填 |
I was just about to leave ______the telephone rang.
| A．while | B．as | C．before | D．when |
— Why don’t you go into the office ,John
—I have ______ my office keys at home.
| A．forgot | B．kept | C．leaving | D．left |
The reason ______she didn’t come to school was_____
she had to look after her sick mother.
| A．because ; why | B．that ; because |
| C．why ; that | D．which ;that |
I smell something ______ in the kitchen. Can I call you back in a minute ?
| A．burning | B．burnt | C．being burnt | D．to be burnt |
— David has studied hard since last term.
— ________ , and ________.
| A．So he has; so you have | B．So he has; so have you |
| C．So has he;so have you | D．So has he; so you have |