A.
B.
C.
D.1
[单选题]A.B.C.D.1
[单选题]A.B.C.D.
[单选题]A.-cosxB.-ycosxC.cosxD.ycosx
[单选题]A.明显下降B.正常或偏低C.增高或正常D.明显增高E.轻微增高
[单选题]A.取得极大值B.取得极小值C.D.