为什么是a dancing lesson而不是dance lesson?

为什么是a dancing lesson而不是dance lesson? 为什么跳舞课要用dancing lesson 是dancing lesson要加s或者a吗 We have a dancing lesson的意思 I have a dance lesson today哪错 There's a sign ___(ask)for dancing lesson lesson have a piano lesson 中lesson可以是复数吗 舞龙是dragon dance,为什么不是dancing? take acting lesson.为什么是acting She has a____(dance)lesson every Thursday I w( ) tired this morning because I had a dancing lesson.