为什么they didn’t konw ( ) with the medice里填what was the matter

为什么they didn't konw ( ) with the medice里填what was the matter而不是 what the matter was /
this is the best way I could think of( )the students ( ）the rules里填to stop/breaking而不是stopping/breaking ．两问请回大为什么?
有两问

为什么they didn't konw ( ) with the medice里填what was the matter而不是 what the matter was
我觉得后者是对的,答案错了.
this is the best way I could think of( )the students ( ）the rules里填to stop/breaking而不是stopping/breaking ．
I could think of是插入的,可以去掉,其实主语是 the best way,那么如果用stopping就必须说 the best way of stopping；如果没有of（因为插入的句子里最后有个of,总不能2个of连用,于是只能the best way to stop...