题目

如图所示,乌鸦后一年的种群数量是前一年的λ倍,下列分析正确的是( ) A.第6年以前乌鸦种群呈“S”型增长 B.第5年和第7年的乌鸦种群数量相同 C.第3年的乌鸦种群增长速率最大 D.第3年的乌鸦种群数量最大 答案：【解析】选D。6．听第9段材料，回答第13--16题．13．When will they take a summer holiday？A．Before exams．B．Before this summer．C．After three more weeks．14．What does the woman want to do during summer？A．Travel to China．B．Teach English to some immigrants．C．Learn Chinese from immigrants．15．Where has the man ever been？A．England．  B．China．  C．America．16．What does the man think of learning a foreign language？A．A person is interested in speaking．B．It's difficult for a person to learn a foreign language．C．A person can speak it，but can't read and write．