工业上常以()为原料在催化剂作用下制备甲胺。
A.甲烷
B.甲醇
C.甲醛
D.氨气
参考答案:B, D
--- Will you waste your time and money on that? --- Certainly ________.
A.I not
B.don’t
C.not
D.no
The girl that Peter had thought of _______ someone to be avoided finally became his soul mate.
A.to
B.upon
C.in
D.as