设$z=\frac{1}{2}+\frac{\sqrt{3}}{2}i$($i$是虚数单位)，则$z+2z^2+3z^3+4z^4+5z^5+6z^6=$（  ）

世界上跨经度最多的大洲和大洋分别是    

给出下列命题：
①函数对称；
②若向量a、b、c满足a·b=a·c且；
③把函数的图象；
④若数列既是等差数列又是等比数列，则
其中正确命题的序号为                                                                                                               （   ）

完形填空

    Natural resources are things that we use that come from the earth. Our natural resources are limited(有限的). This means that they will not1forever. Some are renewable, like when you plant a new tree when you cut one down. Others are not renewable, like when you dig coal(煤) out of the 2Once it is used, it is gone.

    People realize the 3 that the earth's natural resources are limited, and can do things to help conserve(节约) those resources.4you try to conserve a natural resource, you try to use less of it, so it does not get used up so5One way that people conserve fuel, like gasoline, is by riding a bicycle or walking when the6is short instead of driving everywhere.

    Water is a very important natural resource because we all need it to stay 7We can conserve water8making sure that our pipes and taps do not leak(泄露). We can also make wise choices to conserve water, like only using the dishwasher or washing machine when they are full. Everyone can make contributions to protecting natural resources.

何兆武等人认为董仲舒的思想“已经不是先秦儒家的本来面目,而是经过一番改造以适应汉王朝封建统治阶级政治需要的儒家学说”，董仲舒对儒家思想的改造表现为（    ）