本次教学视频后5个问题如下：
1、What are the purposes of an NG tube?
2、What position is the patient in while inserting an NG tube?
3、How does a nurse check the placement of an NG tube afterinsertion?
4、How is the patient measured for NG insertion?
5、What does gavage mean? Hmm, and lavage?
请大家参考教学视频内容，用英语自行作答上述问题。