Thank you.Not at all用于回答谢谢.
It does not matter.不重要,指没关系.
you are welcome你太客气了.和Not at all一样是用来回答Thank you.这个比较常用
c.that is all right.什么也别说了是对的,和you are welcome一样
Not at all.you are welcome.that is all right.It does not matter都表示不用谢
回答问题2,这个词的意思是
出现;显露[C]
John's appearance in the doorway was welcomed with shouts.
约翰出现在门口时,大家高喊着欢迎他.
露面;来到;演出[C]
The singer made her first appearance in a concert in Boston.
这位歌唱家第一次演出是在波士顿的一个音乐会上.
出版[C]
出庭,到案[C]
外貌,外观;外表[U][C]
The appearance of the old house completely changed.
那所旧房子的外观全变了.
景象,现象[C]
表面迹象[P]
[c]指可数 [u]指不可数