他很懒，却在食堂开饭的时候抢占队伍的前几名。却：表示转折。
因为天气冷，所以添加了衣服。因为……所以……，是因果复句的关联词。

例句：今天下雨了，小明却高兴地笑了，因为不用上体育课了。
“却”有表示转折的意思，所以在前面一定会有一个前提条件，这个前提也就是句子中的“今天下雨了”。
“因为”跟在“却”字之后，起的作用是解释转折的原因。为什么下雨了他却很高兴？原来是因为不用上体育课。

都这个时辰了他还没有回来是因为昨夜他喝多了误了火车了。

我们却一直在努力坚持，因为我们有着共同的梦想。

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