I (have) visited my grandparents (from maternal side).
一般过去式和现在完成时都可以,强调是姥姥姥爷而非爷爷奶奶的时候,就用from maternal side(母亲那边的)。
^-^希望我的回答对你有帮助。
I went to see my grandparents.
I paid a vist to my grandparents.
I visited to grandparents.
I visited my grandparents.