There are some warnings in some countries ______ over exploitation of underground water has caused the decline of wetland and increase of desertification.

A．which

B．where

C．what

D．that

帷幕灌浆必须按分序加密的原则进行，下列描述有误的是( )。

A．由三排孔组成的帷幕，应先进行边排孔的灌浆，然后进行中排孔的灌浆

B．边排孔宜分为三序施工，中排孔可分为二序或三序施工

C．由两排孔组成的帷幕，宜先进行上游排孔的灌浆，然后进行下游排孔的灌浆

D．每排孔宜分为三序施工