I went to the swimming pool to swim yeaterday.
如果直接说我昨天去游泳是:I went swimming yesterday
to后的动词要原型,这是不定式结构。
希望对你有帮助。
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go swimming 是一个固定的词组,动词变化的时候,只要改go就可以了。
类似的还有go hiking远足,驴行等等。
直接I went to the swimming pool就行,太强调动作的细节就有点chinglish了