An increasing number of students, year by year, across China ____ hard to realize their dream of studying abroad.

A．is trying

B．are trying

C．will try

D．have tried

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