问题补充：
---Are you taking morning exercise tomorrow?
---Sure. We do sports every morning it rains
A. as long as
B. unless
C. as though
D. in case
答案：
A. as long as
(答案→)B. unless
C. as though
D. in case
解析：连词辨析。A只要；B除非…；如果…不…;C似乎，好像；D以防；句意：明天你要去早锻炼吗？—当然。如果不下雨，我们是天天都要锻炼的。根据句意说明B正确。
