if helping means “sb is helping sb" , then it should be translated to 正在帮助 someone(某人), while help is "帮助某人". So in general, Chinese doesn't have progressive tense, you only need you add "正在" before the verb. And "What r u doing" is “你(you)正在(means progessive tense)做(do)什么(what)?” Likewise, teaching is 正在教, learning is 正在学习, talking is 正在聊天. And we don't really have a specific word for being....normally if we want to say sth is being done, we use 被 to indicate passive voice, so it's like: 正在被+ verb