A.unlessB.untilC.ifShe didn’t leave for the airport （） ……

单项选择题That book gives a very vivid （） of that city.

A.picture
B.photo
C.view

单项选择题The police knew the （） of the accident.

A.cause
B.reason
C.result

单项选择题The pilot turned engine （） and is ready to take off.

A.up
B.off
C.on

单项选择题Progress has been （） in aeroplane design.

A.done
B.made
C.produced

单项选择题The question was so difficult that （） people could answer it.

A.little
B.afew
C.few