There are two________ in the basket. [ ]
A. potatos
B. potatoes
C. potato
D. zoos
答案:B
下列表示化学用语或模型正确的是
A.乙醇分子的比例模型:
B.Cl-离子的结构示意图:
C.N2的电子式:
D.含有8个中子、6个质子的某核素符号:
I()have watched that movie--it'll give me horrible dreams.
A. shouldn' t
B. needn' t
C. couldn't
D. mustn't