I bought a pen to did(还是do?) my homework.

问题描述:

I bought a pen to did(还是do?) my homework.

I bought a pen to do my homework.
to + 动词原形

I bought a pen to (do) my homework.
为了写作业,我买了一支钢笔.
这里要填的是不定式to do,在句子中表示行为的目的,作目的状语.所以空格中要填动词原形,而不是过去式.