look at sb./sth.:看著(某人/某物),如:Look at my eyes and say it again.看著我的眼睛再說壹遍.
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.