题目

---If you        to my birthday party last Saturday, you would have met Jim.    ---I was not in Beijing then, otherwise I       to your party.        A．came; would have come  B．had come; would have come        C．would have come; had come   D．would come; had come 答案：B下列单质的化学式书写不正确的是（　　）A．H2B．He2C．O2D．N2