食物嵌塞是因为
A．卡环臂未进入倒凹区B．基托与粘膜不密合C．卡环过紧D．拾支托凹过深E．有早接触
参考答案：B
---- Did you visit the Big Ben in London?
---- No, we ______ it, but we spent too much time shopping.
A．could visit
B．could have visited
C．must ahave visited it
D．can have visited
下列哪种脂蛋白可以将肝脏合成的内源性胆固醇运转至肝外组织（）
A.CM
B.VLDL
C.LDL
D.HDL
E.IDL
