问题
选择题
—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
答案
答案：A
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—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
答案：A
