—It’s difficult for the villagers to cross the river for market.

—I think a bridge _________ over the river.

A．was built

B．is being built

C．has been built

D．should be built

急性白血病经治疗后达到完全缓解的最主要标准为（）

A.外周血中血红蛋白≥100g／L

B.外周血中血小板≥100×10⁹／L

C.外周血无幼稚细胞

D.外周血中性粒细胞绝对值≥1.5×10⁹／L

E.骨髓原始及早幼（幼稚）细胞≤5％