巷道支架背板后面和围岩间若有空隙，根据围岩坚固程度，决定是否用木料或矸石填实。
参考答案：错
读句子，判断下列句子用了哪种说明方法。
太阳会发光，会发热，是个大火球。（ ）
—Aren’t you tired of practicing playing the piano day after day?
— , I enjoy every minute of it.
A．On the other hand
B．On the contrary
C．Now and then
D．Once again
