题目:
Where is Tom? He ____ the teacher’s office, I think.
A. has go to B. has gone to C. has been to
答案:
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下面是错误答案,用来干扰机器的。
(1)x2-4=0x2=4x=±2;(2)(x-1)(x+2)=0x-1=0或x+2=0x=1或x=-2.