Question

Now most families have only one child ______ our country’s one-child policy.

1. A.
   since
2. B.
   because
3. C.
   because of

Answer 1

C
试题分析：since由于，自从……以来；because因为；because of因为。句意：因为我国的一孩政策，现在许多家庭只有一个孩子。Because和because of都表示原因，区别是前者接从句，后者接名词性短语。下文our country’s one-child policy为名词性短语，故选C.
考点：考查短语辨析