根据短文内容，填写所缺单词，使短文意思完整。每空限填一词。

    Americans like toat each other when they are. If you don't do so, it means you are, or are not interested.

    Americans, "thumbs (拇指)" means "yes", "very good" or "well done", while "thumbs down" means the opposite. To call a waiter, people put oneabove the head. It is all right toat things but not at people with the index finger (食指). Americans point their index fingers at childrenthey scold (责备) them andthem on the head when they praise (表扬) them.

    Learning body language is sometimes difficult. If you don't know what to do, the best thing to do is.