选择中药防霉杀虫的化学药剂应该是
A．价格低廉
B．对人、畜无害
C．毒性小
D．效力高
E．防霉效果持久
参考答案：A,B,C,D,E
下列物质属于苯的同系物的是 [ ]
A．
B．
C．
D．
That helps to explain ( ). businesses are setting up Net sites even though profits aren't yet very big.
A．that B．the reason forC．why D．why that
