单选题 There was at least 2,000 years ago that inhabitants of the Northwest Coast of North America firstestablished trade mutes for obsidian.
【正确答案】 A
【答案解析】答案：A 分析：考点是 it引导的强调句型；把there改成it 即可。 翻译：至少在2000年前，北美西北海岸线的居民就已开始进行黑曜石的贸易运输。