We'll have a picnic in the park this Sunday it rains or it's very cold.A．since B
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We'll have a picnic in the park this Sunday ________ it rains or it's very cold.
| A．since | B．if | C．unless | D．until |
试题答案
C
解析句意：除非下雨或天很冷，我们将在本周日去公园野餐。从句子之间的逻辑关系判断此处应为否定条件句，相当于if...not，故排除if，而选unless。A项since表因果关系。D项until只能引导时间状语从句，故排除。