给出命题：

①函数y=cos$\left(\frac{3}{2}x+\frac{\mathrm{\pi }}{2}\right)$是奇函数；

②若α、β是第一象限角且α＜β，则tanα＜tanβ；

③y=2sin$\frac{3}{2}$x在区间-$\frac{\mathrm{\pi }}{3}$,$\frac{\mathrm{\pi }}{2}$上的最小值是﹣2，最大值是$\sqrt{2}$；

④x=$\frac{\mathrm{\pi }}{8}$是函数y=sin(2x+$\frac{5}{4}\mathrm{\pi }$)的一条对称轴．

其中正确命题的序号是____ ．

“百家争鸣仅仅是现象，藏在其背后的是新形成的代表不同利益的阶级或阶层。”材料揭示了春秋战国时期“百家争鸣”现象出现的主要原因是（   ）

C

    In America, boys and girls often join clubs. The members of a club work together. They also learn certain skills and share good times.

    Many boys belong to Boy Scouts. Boy scouts enjoy hiking and camping out together, and they learn many things. Scouts learn safety rules, first aid, and what to do when in danger. Members have a chance to learn outdoor living. They learn to build fires and cook out in the open.

    Girl Scouts and Camp Fire Girls are clubs for girls. These two clubs give their members a chance to have fun and learn. The girls in a group take trips, have parties and go hiking and camping together. The Camp Fire Girls earn honor beads( 荣誉珠) for learning such skills as swimming and cooking. The Girl Scouts earn badges(徽章).

    Both boys and girls can be members of 4-h clubs, Children who live in either the city or the country may belong to 4-h. A project such as raising a pig or a calf can be carried on only by farm children, while city children can take part in gardening and cooking projects.

    In all these clubs the boys and girls learn to be good and useful citizens.