看两个例句,也许就好明白了: I spend 2 hours on my homework today. 我今天花了2小时时间做作业. It takes me 2 hours to do homework today. 今天做作业花了我2小时时间. spend 用名词或代词做主语,表示谁花费了(钱或时间);take一般用it做主语,表示什么(事情或东西)上花费了(多少钱或时间)
主语是人用spend, 结构: spend..on sth./ spend...(in)doing sth. take用在: it takes sb. sometime to do sth. eg. It took me about two hours to finish doing my homework yesterday. = I spent about two hours (in)doing my homework yesterday.