1. clothes, cloth, clothingclothes统指各种衣服，谓语动词永远是复数， cloth指布，为不可数名词 clothing 服装的总称，指一件衣服用a piece of, an article of2. amount, numberamount后接不可数名词， number后接可数名词 a number of students3. sound, voice, noisesound自然界各种各样的声音，voice人的嗓音，noise噪音I hate the loud noise outside.4. cause, reasoncause 指造成某一事实或现象的直接原因，后接of sth./doing sth，reason用来解释某种现象或结果的理由，后接for sth./doing sth. the reason for being late5. exercise, exercises, practiceexercise运动，锻炼（不可数），exercises练习（可数），practic
