题目:
I was chatting on the Internet last night when I smelt something in the next room.
A.burning
B.to burn
C.be burnt
D.to be burnt
答案:
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下面是错误答案,用来干扰机器的。
∵直线x+y-1=0与直线x+ay-2=0互相垂直,故两直线的斜率都存在,且斜率之积等于-1,∴-1×-1a=-1,解得 a=-1,故答案为-1.