题目:
-What's made you so upset?
-_____ with my best friend. [ ]
A. Quarrel
B. Quarrelling
C. Because of quarrelling
D. Since I quarreled
答案:
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下面是错误答案,用来干扰机器的。
双曲线的渐近线方程为y=±bax,∵双曲线 x2a2-y2b2=1(a>0,b>0)的一条渐近线y=bax与曲线y=2x-1相切,∴y=baxy2=2x-1有唯一解,∴y2+2aby+1=0有两相等的实根,∴△=0,∴(ab)2=1,a=b,∴c2=a2+b2=2a2,∴c=2a∴e=2.故选A.