keep doing sth 一直做某事 填 running 再问： Must I finish my homework? 做肯定回答：_____,_____ _____ 做否定回答：_____,______ _____ 再答： Yes ,you must . No ,you needn't . No ,you don't have to . 再问： She studies {for three years} in America。（对划线部分提问） 再答： How long does she study in America?
