雷州半岛、山东半岛等的特点是[ ]
A．一面临海
B．两面临海
C．三面临海
D．四面临海
答案：C
当窦房结和房室结均出现病变时（双结病变），较易出现（）。
A.房性逸搏
B.交界性逸搏
C.室性逸搏
D.交界性逸搏心律
E.室性逸搏心律
______ is known to us all is that maths is one of the most difficult subjects. [ ]
A. As
B. That
C. It
D. What
