单项选择题
A.picture B.photo C.view
The police knew the （） of the accident.A.causeB.reasonC...
单项选择题The police knew the （） of the accident.
A.cause B.reason C.result
The pilot turned engine （） and is ready to take off.A.u...
单项选择题The pilot turned engine （） and is ready to take off.
A.up B.off C.on
Progress has been （） in aeroplane design.A.doneB.madeC....
单项选择题Progress has been （） in aeroplane design.
A.done B.made C.produced
