—Why does the lake smell terrible?

—Because large quantities of water _____.

A．have polluted.

B．is being polluted.

C．has been polluted.

D．have been polluted.

急性腹膜炎并发严重休克的主要原因是()

A．大量毒素吸收

B．大量液体丧失于腹腔

C．毒素吸收和血容量减少

D．电解质紊乱

E．急性循环衰竭