安全生产责任制的内容主要包括两个方面：一是纵向方面；二是（）。

钻井队多长时间召开一次井控例会？

（）机要职工在通信生产过程中，有权拒绝违章指挥和阻止他人违章作业行为。

苦参中的主要化学成分是（）

A．麻黄碱

B．小檗碱

C．苦参碱

D．东莨菪碱

E．士的宁

以下属于典型后现代主义建筑的是（）。

A.波特兰市政大楼

B.旧金山新联邦大楼

C.纽约新当代艺术馆

D.电话电报大楼

A certain species of bird has two basic varieties, crested and noncrested. The birds, which generally live in flocks that contain only crested or only noncrested birds, tend to select mates of the same variety as themselves. However, if a bird that is raised in a flock in which all other members are crested is later moved to a mixed flock, then that bird—whether crested or noncrested—is likely to select a crested mate. This fact indicates that the birds’ preference for crested or noncrested mates is learned rather than genetically determined. Which one of the following, if true, provides the most support for the argument

A．Birds of other species also tend to show preferences for mates that have one or another specific physical feature.

B．In general there are few behavioral differences between the crested and noncrested birds of the species.

C．Both the crested and noncrested birds of the species tend to select mates that are similar to themselves in size and age.

D．If a crested bird of the species is raised in captivity apart form other birds and is later moved to a mixed flock, that bird is likely to select a crested mate.

E．(E) If a bird of the species is raised in a flock that contains both crested and noncrested birds, that bird shows no preference for one variety or the other in its selection of a mate.