·I was helping my mother is the kitchen all day yesterday.有语病吗？

I helped my mother in the kitchen all day yesterday.
你要表达的是过去时，所以应该用动词的过去式。
你的句子说的是I was helping...这是过去进行时，过去进行时是当你在表达过去的具体某个时间是后用的。
这句话需要改为：I was helping my mother in the kitchen at this time yesterday.
at this time是个具体的时间，可以用过去进行时。
而这句话中，要用过去时。

I helped my mother in the kitchen all day yesterday

把was helping改为helped

is改为in

yesterday,I helped my mother in the kitchen the whole day