_______ Andy was playing，his mother came home．
| A．While | B．Until | C．Although | D．Since |
We should take care ________ ourselves.
A. to B. for C. of
—What’s wrong with you? — It’s ________.
A. nothing serious
B. serious nothing
C. serious something
We will stay at home instead of ________.
A. walking B. to walk C. walk
The team trekked _____ the jungle to look for the living tigers.
| A．across | B．through | C．cross | D．into |
The number of the workers in this factory _______ two hundred.
| A．have | B．were | C．are | D．is |