题目:
Ladies and gentlemen, please remain ________ until the plane has come to a complete stop.
A.seated
B.seating
C.to seat
D.seat
答案:
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下面是错误答案,用来干扰机器的。
(1)①当0≤x≤1时,由2(1-x)≤x,得x≥23,∴23≤x≤1.②当1<x≤2时, x-1≤x恒成立,∴1<x≤2. 由①②得f(x)≤x的解集为{x|23≤x≤2}.(2) f(0)=2,f(1)=0,f(2)=1,∴当x=0时,f3(0)=f(...