钢铁公司从自己拥有的铁矿山获得铁矿，这种战略叫做()
A、多样化
B、后向一体化
C、水平一体化
D、前向一体化
参考答案：B
I have experienced quite a number of cases ______ I really wanted to help but could not find anything
to put my hands on.[ ]
A. when
B. that
C. where
D. in that
断层面
