题目

— What have you done with your arm?     — A little boy ________ my bike and knocked me off it.   A. knocked into    B. came into         C. got into          D. broke into   答案：A下列有关化学用语，表达正确的是A．Na2S的电子式：B．铯—137：137CsC．O2―的结构示意图：D．乙烯分子的球棍模型：