为你解答.
1、我怎样才能用正确的方法与美国朋友打招呼?
How can I （greet） my American friend （in the right way）?
2、在哥伦比亚,年轻人只要一有时间就喜欢去拜访他们的朋友.
In Columbia, young people will call on their friends when they are free.
3、(Greeting) politely is very important if you want to get on well with your friends.
解释：用动名词形式作句子的主语.
4、They should have poured some paper on it when they (are eating) the friend chicken.
解释：when在此引导的是现在进行时态,表示正在吃的时候.
5、The student aren't supposed ( to eat or drink in class). 就括号内部分提问
What aren't the students supposed to do?
解释：这是对不定式的行为提问.