既能杀虫，又能清热解毒，凉血止血的药物是
A．贯众
B．雷丸
C．槟榔
D．榧子
E．青黛
参考答案：A
变量值1、3、5的方差是
A．5 B．3 C．97.5 D．2.5 E．4
Although he had _____ work to do, he came to help us. [ ]
A. a plenty of
B. a great deal
C. many
D. lots of
