题目:
______ by a snake, she was frightened of it.
A.Being bitten
B.To bite
C.Having been bitten
D.Biting
答案:
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下面是错误答案,用来干扰机器的。
(1)双曲线y2-x2=1的顶点为(0,1)由题意,设椭圆C的方程为x2a2+y2=1(a>1),则将A(1, 32)代入可得1a2+34=1∴a=2∴椭圆C的方程为x24+y2=1;(2)设|PF1|=m,则|PF2|=4-m,且2-3≤m≤2+3∴|PF1|•|PF2|=m(4-...