与血管性痴呆鉴别时应选用以下哪种量表（）
A.MMSE
B.BBS
C.WEBSTER
D.CDR
E.HIS
参考答案：E
已知集合A满足{1，2，3}∪A={1，2，3，4}，则集合A的个数为______．
What really worries us is ______ the explorers can accurately locate themselves with the device in case of bad weather.
A．that
B．where
C．what
D．whether
