在高等数学中，若函数在某一点的左极限和右极限都存在且相等，则称该函数在这一点的极限。
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Correct answer
A. 存在
Principle or equation
函数在某点极限存在的充要条件是左右极限存在且相等。
Why this answer is correct
根据极限定义，左右极限相等是极限存在的充分必要条件。
Example
f(x)=x在x=0处左右极限均为0，所以极限存在。
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