Oil prices have risen by 32 percent since the start of the year,______ a record US $ 57.65 a barrel on April 4.A. reached B. reaching C. to reach D. to be reaching 答案:B 解析: 略外来物种侵入到一个新的环境,可能会
①其种群数量在一段时间内呈“J”型增长 ②其种群可能会威胁到境内物种多样性
③其种群数量增长不受天敌等外界因素的制约 ④其种群会由于不适应环境而被淘汰
A.①②③ B.①③④ C.②③④
D.①②④