咽痛音哑，目赤肿痛，麻疹不透，常选用的药物是（）
A.柴胡
B.蝉蜕
C.葛根
D.升麻
E.桑叶
参考答案：B
My laptop computer, _______ I can’t go on with my work, broke down the other day.
A．for which
B．which
C．without it
D．without which
什么叫人工授精？试述人工授精的优越性。
