Everyone wants to live in a beautiful, comfortable and “livable” place, but not ______ know where it is.

A．all

B．some

C．either

D．both

胆固醇结石形成的最主要原因是

A．胆汁成分改变

B．胆道感染

C．胆道梗阻

D．葡萄糖醛酸酶增加

E．胆道内蛔虫残体留存