Many things _____ impossible in the past are common today.

A．considered

B．to consider

C．considering

D．being considered

主动脉夹层的病因与下列因素无关的是（）

A.外伤

B.动脉粥样硬化和高血压

C.动脉囊性中层坏死

D.风湿性心脏病

E.医源性损伤