___________和___________的作用是血栓形成中相互促进的两个主要环节。
参考答案：凝血酶 、血小板
We have heard what he has said; we are waiting to see he will do. [ ]
A．how
B．what
C．when
D．that
标准正态分布曲线下90%所对应的横轴尺度u的范围是
A．-1.645到1.645
B．-∞到1.645
C．-∞到1.58
D．-1.96到1.96
E．-2.58到+∞
