Why don't you do sth.?/ Why not do sth.? 后面的是前面的缩略形式.为什么不做……? What/ How about doing sth,? 做……怎么样? Let's do sth. 让我们做……吧! Shall we do sth? 我们做……好吗? You had better (not) do sth. 你最好做(不做)…… Would you like to do sth./ sth.? 你想要做……/ 你想要……? Would you please do sth.? 请……好吗?