烯烃和炔烃可与氢发生（）。
A、取代反应
B、置换反应
C、加成反应
D、不反应
参考答案：C
Daniel is good at _____ lessons. [ ]
A. all his
B. his all
C. the all his
D. his the all
呼吸节律是怎样产生和维持的？
