默写舞幽壑之潜蛟

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                                                                Table manners in America

        Don't circle your plate with your arms. If you do so, you will become the focus  (焦点)  of the table. Everyone would wonder, "Is there anything wrong with the food?" This may give a wrong message that you don't like the food or something like that.

       Don't push the plate back when finished. Leave it where it was. Do you want to let the hostess (女主人)(1)_________(know ) that you've just done a labours。

        Don't lean (倚靠) back and say "I'm through" or "I'm full". Just put the fork and knife across the plate. That's all. 

       (2)Don't cut up everything before you start to eat. Cut only one or two bites (块) at a time. Never take a huge mouthful of anything. Do you want to show how hungry you are? Don't do that. It's not so good.

        It's never good to reach across the table for anything. If the thing you want is not at hand, simply ask the nearest person for help, like "(3) Mrs. Smith, could you pass me the dish?"

根据如图中的实验装置，回答问题：