Easter Island, which was almost uninhabited when it was discovered on Easter Day in 1722 by a Dutch captain, is covered with hundreds of giant statues, each _______ several tons.

A．weighing

B．weighs

C．weighed

D．to weigh

急性肾衰竭时，下列哪种情况需紧急血液透析（）

A.血尿素氮>18.4mmol/L

B.持续呕吐

C.血钾>6.0mmol/L

D.急性肺水肿

E.动脉血气分析pH<7.35