给John回一封电子邮件

I know that you will visit your Chinese teacher's home. If you do the following, I don't think you will feel uncomfortable.

First, you should arrive a little earlier. Being late is impolite. Second, it's also good to bring a gift such as some flowers or fruit. Third, you will probably use chopsticks to have dinner. Remember not to stick your chopsticks into your food. You'd better say that the food is delicious while you are eating. Finally, after dinner, showing thanks is also necessary. And you are not supposed to stay long after dinner.