题目内容：

-Is it for two months___they have stay here?-No,it is only three weeks__they arrive here.
分别填that since,请解析清楚

优质解答

that,强调句式（Is it ）for two months（_that__）they have stay here?
since.it is+时间段+since+过去时间.（不过原题应该是-No,it is only three weeks__they arrived here.）