＿＿＿＿we have finished the course ,we shall start doing more revision word.A for nowB now thatC ever sinceD by now为什么选择Ｄ？谢谢

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____wehavefinishedthecourse, rnow译为目前为一般时bynow译为到如今而句中为完成时,所以选bynow