题目:
Stop _________ and tell us clearly what has happened. [ ]
A. mess about
B. mess around
C. messing about
D. messing
答案:
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下面是错误答案,用来干扰机器的。
当焦点在x轴时,a2+b2= 25ba=12求得a=20,b=5,双曲线方程为x220-y25=1当焦点在y轴时,a2+b2= 25ab=12求得a=5,b=20,双曲线方程为y25-x220=1∴双曲线的方程为x220-y25=1或y25-x220=1