— I'm not sure ________ there are living things on other planets or not. — Even scientists aren't su...
2022-10-08 05:26:51 139次 人教新目标英语九年级全册 Unit 2 Section A (1a－2d) 复习训练题 2018年 单选题 反馈错误 加入收藏 正确率 : 100%
题目内容：
— I'm not sure ________ there are living things on other planets or not.
— Even scientists aren't sure about it.
A. whether B. where C. why D. that
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