可以啊.
We think it our duty to clean our classroom every day中to clean our classroom every day是形式宾语it所指的事情,本句是"主谓宾补"句式.
而We think it's our duty to clean our classroom every day.中it's our duty to clean our classroom every day是宾语从句.
所有这种"主谓宾补"的句子均可以改为含宾语从句的复合句,因为宾语和宾语补足语之间本身就是逻辑主谓关系.