Some pre-school children go to a day-care center, ___ ___ they learn simple games and songs.

A．then

B．there

C．while

D．where

根据白血病细胞形态符合急淋型白血病的特点是：（）

A.原淋细胞体积增大

B.大细胞为主

C.细胞大小一致

D.临床少见，预后差

E.体积较小，细胞形态比较一致