【单选题】下列哪种元素在强酸性土壤上的有效性低 。
【单选题】幻灯片放映时,按( )键可以终止幻灯片放映。
【单选题】生态系统物质循环的特点 不包括 A. 具有全球性 B. 在生态系统的各营养级之间循环往复 C. 在群落与无机环境之间循环往复 D. 物质是指组成生物体的基本元素
【判断题】任何数列都可能存在单调子列,也可能不存在单调子列。
【单选题】Why does Colonel Ludlow move his families to a remote part of Montana?
A.
Because he dreams a better life in the mountainous area.
B.
Because he is tired of the fact that the American government betrays the Native Americans.
C.
Because the Native Americans betrays the American government.
D.
Because there are more business opportunities.
【简答题】Why does Colonel Brandon tell his story to Elinor?