試題詳解

18. Since early summer, the combination of drought and rising sea levels has helped drag salty water from the ocean up the Mississippi River. The high levels of saltwater have made much of the region’s water undrinking. But public health  experts have also voiced worries that the saltwater intrusion could over time,  corrode the region﹁S ageing water infrastructure.
(A)the combination of drought and rising sea levels
(B)undrinking
(C)have also voiced
(D)over timecorrode
(E)corrode