【题目】Bears __________ fat stores throughout the summer and fall to have energy enough to last them through their winter sleep.
A. pack up B. build up
C. bring up D. take up
在线课程【答案】B
【解析】句意：黑熊在整个夏天和秋天积蓄的脂肪足够它们维持整个冬眠期。build up逐渐增加；符合句意。pack up停止，收工；bring up抚养，使……长大；take up开始从事，占据。故选B。