A napkin, "napkin," is like a little towel that you use. 餐巾（napkin），是你使用的一种小毛巾。

In case you need to wipe your face while you are eating, you can use your napkin, 如果你在吃饭的时候需要擦脸，你就可以使用餐巾。

and it's common in American restaurants and in houses for people to put the napkin on their legs while they are sitting, on the top of their legs,  人们坐着的时候把餐巾放在腿上，这在美国的餐馆和家庭是很普遍的现象，腿的上半部，

which we would call the lap — on your lap, "lap," you put the napkin while you are eating. 我们称之为膝部（lap）——你在吃饭的时候把毛巾放在腿上。

To set, "set," the table means to put all of the things that you need on the table — plates, spoons, knives, forks, and so forth. 摆（set）餐桌是指把所有需要的东西都放在桌子上——盘子、调羹、刀、叉等等。

That is to set the table — to make the table ready so you can eat. 这就是摆餐桌——摆好桌子吃饭。

"About 15 minutes" after I set the table, my wife and I sit at the table — "we sit down at the table in the dining room and talk about our long day." 摆好餐桌后“大约15分钟”，我妻子和我坐在餐桌旁——“我们坐在餐桌旁边，聊着我们漫长的一天”。

The dining room, "dining," is a place where you eat. 餐厅是吃饭的地方。

To dine, as a verb, "dine," means to eat. 动词“dine”是“吃饭”的意思。

So, the dining room is the room in your house where you eat your meals. 因此，餐厅就是你房子里吃饭的地方。