阿司匹林预防血栓形成的机制是（）
A.抑制血栓素A合成
B.促进前列环素的合成
C.促进血栓素A合成
D.抑制前列环素的合成
E.抑制凝血酶原
参考答案：A
(2013·济南二模)It was during the Ming Dynasty ________ the Great Wall was repaired and extended to take on the appearance it has today.
A．when
B．which
C．what
D．that
表层固井使用插入式方法有那些优点？
