A.+→
B.→+
C.+→
D.→+
答案:D
若函数f(x)=2x+1,则f[f(x)]等于( )
A.4x+3
B.4x+4
C.(2x+1)2
D.2x2+2
—My good friend, Mike, wants to be a soldier when he grows up.
—So ____ I. [ ]
A. do
B. am
C. will
D. should