Question

Now most families have only one child _____ our country’s one-child policy.
A.  since        B. because           C. because of

Answer 1

C

解析试题分析：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