【答案解析】因he will return to his native land中用的是将来日才，所以不能选[C]。实际上，该题是对时间状语before long的强调，即是涉及到强调句的内容。答案为[B]。若选[A]，应为 It was long before that he returned to his native land(很久以前，他回到了祖国。)若选[C]，应为It won't be long before he returns to his native land．(不久，他返往祖国。)