Complete the sentences.use for or since. 1)the boys are tired.they have been playing hour and half.2)alex has been talking on the came home 3)the telephone has been about a minute.why doesnt some one answer answer it? 4)mr williams has been writing his half a year and hasnt fifnished it yet 5)people have been working on thus the beginning of the century 6)john has been washing his car nine oclock this morning 7)sarah has been waiting for her sister a long time