Most birds find it safe to sleep in the trees, but ____ they have eggs or young

Most birds find it safe to sleep in the trees, but ____ they have eggs or young

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Most birds find it safe to sleep in the trees, but ____ they have eggs or young chicks, they don’t use a nest.
A.whyB.howC.unlessD.where

答案
C
解析
unless引导让步状语从句,意为“如果不”。根据they have eggs or young chicks和they don’t use a nest可判断出前句是后句的条件,表示“如果它们不下蛋或没有小鸟,它们就不用窝”。why用于引导名词性从句或定语从句,意为“为什么”。how引导名词性从句,意为“如何”,表示动作的方式。where引导名词性从句或定语从句,意为“在……地方”。
举一反三
Help others whenever you can ______ you will make the world a nicer place to live in.
A.andB.orC.unlessD.but

题型:不详难度:| 查看答案
We had to wait half an hour _______ we already booked a table.
A.sinceB.althoughC.untilD.before

题型:不详难度:| 查看答案
He was told that it would be at least three months ___ he could recover and return to work.
A.whenB.beforeC.sinceD.that

题型:不详难度:| 查看答案
I’d like to study law at university __________ my cousin prefers geography.
A.thoughB.asC.whileD.for

题型:不详难度:| 查看答案
Many of them turn a deaf ear to his advice, _____ they knew it to be valuable.
A.as ifB.now thatC.even thoughD.so that

题型:不详难度:| 查看答案
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