1．Those cats ____________(scream) for hours．
答案：have been screaming
2．We ____________(wait) for him for two hours．
答案：have been waiting
3．The dollar ____________(climb) steadily all week．
答案：has been climbing
4．He ____________(help) himself to my stationery．
答案：has been helping
5．The children ____________(enjoy) themselves for a day．
答案：have been enjoying
6．She is very tired．She ____________(work) all morning．
答案：has been working
