Try to compare:
(1) Find a point m on the straight line to make MP+MQ the shortest.
(2) Find a point M on a straight line so that there is a shortest polyline, and the points M, P and Q are all on it.
The problem (1) can be solved by symmetrical points, and the problem (2) is not equal to (1), because the length of this polyline is not necessarily MP+MQ, but it can also be MP+PQ or MQ+PQ in the case of three points. Considering these three situations, choose the shortest scheme, and the answer is of course the same as (65438).
Because this is a water pump, you only need to connect M, P and Q with a dotted line, so it is problem (2).