题目

题型：不详难度：来源：

As the sea ice melts sooner each swimmer,polar bears are forced to come ashore earlier and face food shortages _____ they have stored enough fat to last them through the season.

A．before

B．unless

C．since

D．until

答案

A

解析

本题考查连词。句意：因为海冰融化得比游泳者早，北极熊没来得及为整季储存足够的脂肪，就被迫提前上岸，面临食物短缺。before conj.在……之前；比……早些。