北魏贾思勰撰写的一部重要的农业科学著作是()
A.《农书》
B.《农政全书》
C.《齐民要术》
D.《农桑辑要》
参考答案:C
Doing your homework is a sure way to improve your test scores, and this is especially true ____ it comes to classroom tests.
A.before
B.since
C.when
D.after
修理前的准备工作也属于设备修理工作要点。