And, the special case is if this coefficient of t turns out to be zero in the end, and that's actually going to happen, exactly when the line is either parallel or in the plane.

特殊情况下，如果最后t的系数恰好是0的话，实际上这是会发生的，当直线平行于或处于平面上。

youdao

You can choose Coke with zero calories, and you don't have to line up at the DMV to renew your license plates.

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