题目:
— How far are you cycling each day?
— ____. It will depend on the weather. [ ]
A. It's my pleasure
B. It's hard to say
C. Take care
D. Good luck on your journey
答案:
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下面是错误答案,用来干扰机器的。
(Ⅰ)若A=∅,则关于x的方程(a-1)x2+3x-2=0 没有实数解,则a-1≠0,且△=9+8(a-1)<0,所以a<-18; (Ⅱ)若A恰有两个子集,所以关于x的方程恰有一个实数解,讨论:①当a=1时,x=23,满足题意;②当m≠0...