题目内容
1. Most birds find it safe to sleep in the trees, but _____ they have eggs or young chicks, they don’t use a nest.
A. why B. how C.unless D. where
【答案】
C
【解析】略

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题目内容
1. Most birds find it safe to sleep in the trees, but _____ they have eggs or young chicks, they don’t use a nest.
A. why B. how C.unless D. where
C
【解析】略