What have you been doing?请问have been是固定搭配啊,为什么要拆开呢,可以改成what

What have you been doing?请问have been是固定搭配啊,为什么要拆开呢,可以改成what what have you been doing what you have been doing - What have you been doing recently? What have you been doing late have been wrong是固定搭配么? What have you been doing since we last met? What have you been doing 怎么用recent添 Celia asks,"What have you been doing these days?" by the way,what have you been doing. what have they been doing 是什么时态 what have u been doing的been是什么时态?