________ a lot of trees in this area, but now we can see a tall building instead.

A．There used to have

B．There used to be

C．There is used to having

D．There is used to being

确定扩底灌注桩扩底端尺寸时，下述（）不正确。（）

A.当持力层承载力低于桩身混凝土受压承载力时，可采用扩底

B.钻孔桩扩底端直径与桩身直径的比D/d一般宜为3

C.扩底端侧面斜率一般取1／4～1／2

D.扩底端弧形底面的矢高一般取（0.1～0.15）D