Tìm lỗi sai và sửa lại

==>Tìm lỗi sai và sửa lại:
1/ However Alex is an America, he plays Vietnamese folk games well.
2/ It is necessary for me to tip in a coffee shop?
3/ I went to the post office immediately since I left you.
4/ The traditional vietnamese wedding is one of the most important ceremony in vietnamese culture.

*Help:)) tặng 5sao*