Helen said that she would come to see me the next day, but she_____.

A．wouldn’t

B．hasn’t

C．hadn’t

D．didn’t

对背水侧反滤排水设施要注意观察分析（）和保护层有无淤塞现象。

A.透水

B.反滤

C.颗粒均匀

D.反滤料