题干
—__________
—It's ten o'clock.
A：What color is it?
B：What's the time?
C：What's this in English?
答案(点此获取答案解析）
B
—__________
—It's ten o'clock.
A：What color is it?
B：What's the time?
C：What's this in English?
=7.8×103 kg／m3）制造，耗钢130吨；若采用“气凝胶”代替钢材来制造一架同样大小的 飞机，则需“气凝胶”的质量为 ( )
