[单项选择]

Every minute of every day, what ecologist James Carlton calls a global "conveyor belt" redistributes ocean organisms. It’s a planet wide biological disruption that scientists have barely begun to understand.
Dr. Carlton—an oceanographer at Williams College in Williamstown, Mass. —explains that, at any given moment, "there are several thousand [marine] species [traveling].., in the ballast water of ships. " These creatures move from coastal waters where they fit into the local web of life to places where some of them could tear that web apart. This is the larger dimension of the infamous invasion of fish destroying, pipe-clogging zebra mussels.
Such voracious invaders at least make their presence known. What concerns Carlton and his fellow marine ecologists is the lack of knowledge about the hundreds of alien invaders that quietly enter coastal waters around the world every day. Many of them probably just die out. Some benignly
A. their knowledge of this phenomenon is limited
B. they believe the oceans are dying
C. they fear an invasion from outer-space
D. they have identified thousands of alien webs

最新试题

• ●    [多选题]因工作需要,公司系统员工需借用到系统外单位的,由借出单位报各单位人力资 源管理部门审批后,
• ●    [填空题]在发生 、 时，员工应主动维持秩序，对乘客进行引导。
• ●    [判断题]变电检测管理分级负责原则指一类变电站执行国网评价中心、省评价中心、省检修公司三级检测机制；
• ●    患者，女，29岁，患红蝴蝶疮，斑疹黯红，关节痛，足跟痛，伴不规则发热，手足心热，心烦失眠，疲乏无力，
• ●    [单选题]《“家庭亲情贷”管理办法》规定：原则上生产型农户授信额度不超过家庭年净收入的（ ）倍，种
• ●    根据支付结算法律制度的规定，下列有关贷记卡的表述中，正确的有（）。