咳血的病因为
A．感受风热燥邪
B．肝火犯肺
C．肺阴素虚
D．虚火灼伤肺络
E．劳伤过度
参考答案：A,B,C,D
一元二次方程x2-ax+6=0，配方后为（x-3）2=3，则a=______．
— Jack! You are wet through. Didn't you listen to the weather report this morning?
— No, I didn't. I was in a hurry. Besides, it ______ when I left. [ ]
A．was raining
B．wasn't raining
C．would rain
D．Hadn't rained
