题干
—______________
—Because I am very cold.
A：How do you put on your coat?
B：Why do you put on your coat?
C：Why do you take off your coat?
答案(点此获取答案解析）
B
，给出下列四个命题
；②若
；③若
；④若
)满足条件(8—)·=30，则x= ( )