look down：向下看,不帶賓語,如：Don't look down while you are on the edge of the cliff.在懸崖邊上別往下看.
look at sb./sth.：看著（某人/某物）,如：Look at my eyes and say it again.看著我的眼睛再說一遍.
look down at sb./sth.：低頭看（某人/某物）,如：She looked down at her toe and murmured something.她低頭看著自己的腳趾,小聲嘟噥著.
look down on/upon：看不起,小看（某人）,如：You shouldn't look down on someone else because he is poor.不要因為別人窮而看不起他.