分类：教育/科学-学习帮助
问题：单项选择20.whenigothome,myson_______ 
20.when i got home, my son __________ his homework already. he __________ tv at that time.a.was doing, was watching b.had done, had watch c.was doing, had done d.had done, was watching
回答：already,when i got home提示用过去完成时,第一空应该是had done

at that time提示用过去进行时，第二空应该是was watching 

选择Ｄ