When exchanging business cards with a Chinese visitor, present yours with both hands, with the card facing them. If you don't have a business card with you, apologize, accept their card and thank them. Take time to look at their business card. For example, if a visitor declines a drink the host would not drink either. In Chinese culture it is polite to decline offers of food or drink at least three times before accepting.
Toasting is important in China, with the host making the first toast.
Chinese guests will never finish all the food on their plates because doing so signifies that they are still hungry. Giving a small gift to one of the Chinese fellows as a thank you for speaking to your class is an appropriate gesture. Gifts should not be wrapped in white or black paper, colors often associated with a funeral. Bright colors are preferable. Proper gifts include hats, pens, t-shirts with logos, local memorabilia such as Indian arts and crafts and fine chocolate.