并发操作带来的问题主要有（），（），（）。
参考答案：丢失修改；不可重复读；读脏数据
When they went into the shop and asked to look at the engagement rings, the girl brought out a cheaper one, _______ she had arranged with James.
A．the which was what
B．what was that
C．which was what
D．that was that
预防职业中毒的综合措施？
