根据短文内容和所给汉语提示填空，每空一词。

     Around the world, people have different ideas about what good table manners are. If you drop by

your___1___ (朋友的)homes in the United States, it's better to___2___ (到达)on time. When you

arrive, you don’t need to take off your shoes, most Americans___3___ (穿)their shoe in their homes.

But you will be____4___ (期盼)to make yourself at home by your host and hostess. At table, you should get used to eating with a___5___ (刀), a___6___ (叉子), and a ___7___(汤匙), and trying not to be

noisy when eating. It's rude to speak with your mouth full.

     In China people usually reach for food___8___ (用)chopsticks. It's rude to reach across the table

or in front of someone to get something. Besides, when the meal is___9___(结束), you are supposed

to lift your glass and say " ___10___(干杯)" to toast longevity (长寿), good health or success of the

host or hostess.

     Every culture has its own rules, but people all over the world agree that being well-mannered really

means being kind to others and helping others．

将等量萌发的种子和在沸水中煮过并自然冷却后的种子分别放入甲、乙两试管中，如图所示（本实验中石蜡油短期内不影响生物的生长）。两试管中均无空气存在。据图分析回答：

甲试管放置几个小时后，管内顶部出现气泡，其中的气体成分主要是（）；将该气体引入（）溶液中，可使该溶液变混浊。