In an earlier lesson, you've learned the following sentence.
| You must not smoke here. | ここ で タバコ を 吸って は いけません。koko de tabako o sutte wa ikemasen. |
You can ask people to refrain from doing something in a friendlier way by using the plain form which ends in ない, and follow it with でください.
| Please don't smoke here. | ここ で タバコ を 吸わないで ください。koko de tabako o suwanaide kudasai. |
| Please don't forget (it). | 忘れないで ください。wasurenaide kudasai. |
| Please don't drink a lot of alcohol. | お酒 を たくさん 飲まないで ください。osake o takusan nomanaide kudasai. |
| Please don't ask him anything. | 彼 に 何も 質問しないで ください。kare ni nanimo shitsumonshinaide kudasai. |
