______ scientists have learned a lot about the universe, there is much we still don't know. ( 章节：1 难度：2)_做题室

单项选择题______ scientists have learned a lot about the universe, there is much we still don't know. ( 章节：1 难度：2): A、Once; B、Since; C、Though; D、Unless

正确答案：C
答案解析：
关注下方微信公众号，在线模考后查看

热门试题