— Look! Everything here is under construction.    

— Oh, it has the museum once_________for exhibitng art works been pulled down,too.    [ ]

A. being built    

B. been built    

C. having been built    

D. built

慢性粒细胞白血病急性变最常见的类型是（）

A.急性粒细胞白血病

B.急性淋巴细胞白血病

C.急性单核细胞白血病

D.急性混合细胞白血病

E.中枢神经系统白血病