三盒草莓用英语可以说成 "three boxes of strawberries"。
"Box" 是英语中的盒子的意思，而 "strawberry" 是草莓的意思。这里用了 "of" 连接主语和宾语来表示所属关系。
例句：
I bought three boxes of strawberries at the farmer's market. (我在农贸市场买了三盒草莓。)
Can you please bring me three boxes of strawberries from the grocery store? (你能帮我从杂货店里拿三盒草莓吗？)
I had to throw away three boxes of strawberries because they were moldy. (我不得不扔掉三盒草莓，因为它们变质了。)