一个有理数的平方是它本身，则此有理数是______．
因为02=0，12=1，所以此有理数是0或1．
As there was not much chance to find good jobs in their hometown, a lot of young people tried
to ________ their fortune in cities.[ ]
A. find
B. find out
C. seek
D. look
胺碘酮的药理作用不包括（）
A.阻滞K+通道
B.阻滞Na+通道
C.阻滞Ca2+通道
D.阻断M受体
E.阻断β受体
