Write the equation for the vertical line that passes through the point (-7,5)

题目

Write the equation for the vertical line that passes through the point (-7,5)
我感觉这题没讲完~

答案

翻译：写出过点（-7,5）的垂直线的方程.
但是为什么只有一个点呢?过一个点怎么有垂线呀?