英语翻译
When you visit someone,it's the custom to bring a small gift.
you aren't supposed to arrive early.
If you want to bring someone,you're expected to call first and ask.
you're supposed to check with the host.
it's not acceptable to arrive without
calling first.
翻译下这几个句子,再告诉我句中的：is the custom to
aren't supposed to are expected to are supposed to
is not acceptable to