I spent half an hour on my homework yesterday.（保持原意

题目

I spent half an hour on my homework yesterday.（保持原意
l ( )half an hour ( )my homework skirt.

答案

i took half an hour to do my homework yesterday(ps:此外,还可用cost …on…这三个是固定搭配,可以互换,只不过这个多表示花费金钱做某事)