He worked in this company （） several years.

单项选择题The （）of employees in this company has doubled.

A.sum
B.amount
C.number

单项选择题The Europeans （）to stay ahead in aeroplane design.

A.failed
B.missed
C.lost

单项选择题Mary （） into the room.

A.burst
B.crashed
C.hit

单项选择题The war （） in 1937.

A.broke up
B.broke off
C.broke out

单项选择题She was sleeping with （） windows.

A.empty
B.open
C.wide