与胆碱受体有关药物分类不包括()
A.M胆碱受体激动剂
B.乙酰胆碱酯酶抑制剂
C.M胆碱受体拮抗剂
D.N胆碱受体激动剂
E.N胆碱受体拮抗剂
参考答案:D
4的平方根是( )
A.±2
B.2
C.-2
D.16
–Where is Tom? --He _______ the USA. He _______ back in two months.
A. has gone to; comes B. has been to; will be
C. has been to; comes D. has gone to; will be