He had to stay at home the heavy rain.A because B since C because of D so

He had to stay at home the heavy rain.
A because B since C because of D so

解析：because of与because 意思是一样的，但后面不能用从句，只能用名词。鉴于” because 是连接句子的，而becuase of 中，因为of是介词，所以后面是加名词或名词性短语。 since多为陈述性的事实，相当于“既然” ，since 表示原因时放在句首，侧重于表示“既然如此。so是因此的意思，一般句子前部为原因，后部为导致的结果，故选C。

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