You need decent clothes when you go to church. 你去教堂时要穿着得体。

OK. I will choose something formal. 好吧。我选一套正式的衣服。 

When you are going to visit friends，you'd better telephone them ahead. 在拜访朋友前，最好提早给他们打电话。

When you are going to visit friends，you'd better telephone them ahead. 在拜访朋友前，最好提早给他们打电话。

Tradition again, isn't it? 又是习俗，是吧？