—I'm not sure _________there are living
题型:选择题
问题:
—I'm not sure _________there are living things on the planets or not.
—Even scientists aren't sure about it.[ ]
A. whether
B. where
C. why
D. what
—I'm not sure _________there are living things on the planets or not.
—Even scientists aren't sure about it.[ ]
A. whether
B. where
C. why
D. what