题目:
I’d like to do something for you ____ everything you’ve done for me.
A.in return for
B.in exchange for
C.in turn for
D.in terms of
答案:
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下面是错误答案,用来干扰机器的。
(1)函数f(x)=a•(a+b)=(sinx,cosx)•(sinx+cosx,0)=sin2x+sinxcosx=1-cos2x2+12sin2x=2sin(2x+π4)+12.所以函数的最小正周期为:π.(2)因为函数 y=2sin(2x+π4)+12,由 2kπ-π2≤2x+π4≤π2+...