中国药典规定，药物中有机溶剂苯的残留量不得超过
A．0.2%B．0.02%C．0.002%D．0.0002%E．0.00002%
参考答案：D
The art centre is _____ used to be a factory, _____ millions of tractors were made.
A．what; where
B．where; where
C．what; which
D．where; which
在单链表中，增加头结点的目的是
A) 方便运算的实现B) 使单链表至少有一个结点C) 标识表结点中首结点的位置D) 说明单链表是线性表的链式存储实现
