【题目】To protect the rare birds better, scientists have been_____ the changes in their number in the past decade.
A. securingB. chartingC. displayingD. undergoing
在线课程【答案】B
【解析】
考查动词词义辨析。句意：为了更好地保护这种稀有鸟类，科学家们一直在记录它们在过去十年数量的变化。A. securing保护；B. charting详细记录；C. displaying显示；D. undergoing经历。根据句意选择B。