锂盐的毒性反应主要是A．恶心、呕吐 B．甲状腺功能低下 C．骨髓抑制 D．中枢神经系

容量是56升的铁桶，装满油，取出（x+1）升后，桶内还剩油______升．

Will was stupefied with exhaustion, and he _____ his head on the grass under one of the trees and slept, but he saw a cat acting strangely. 

A．should have lied

B．ought to have lay

C．might have laid

D．must have laid

Tom got addicted to chatting and playing e-games on the net, which made his father ________.

Which of the following is not suitable?

A．on cloud nine

B．hot under the collar

C．feel blue

D．down in the dumps

公路建设项目环境影响评价，是指对公路建设项目过程中可能造成的环境影响进行分析、预测和评估，提出预防或者减轻不良环境影响的对策和措施，并进行跟踪监测的方法与制度。

下列叙述中正确的是( )。

A．线性链表是线性表的链式存储结构

B．栈与队列是非线性结构

C．双向链表是非线性结构

D．只有根结点的二叉树是线性结构