Guo taiming , in    company a number of workers committed suicide, made an apology to the public at the end of May.

A．which

B．whose

C．who

D．that

两曲面体相交时，它的交线一般为封闭的空间曲线，称为（）。

A.相交线

B.相贯线

C.相切线

D.叠加线