分类：教育/科学-学习帮助
问题：快帮忙！！！！！！！！~~~~~~~()wehavefinish 
(  )we have finish our work,let us take a rest。我填的是as，但正确答案是now that。我觉得句意都通啊。请问为什么不能用？
回答：now that 既然
as做因为解释时一般不放句首.如I must stop writing, as I have a lot of work to do.