远主焦点

Reflector telescope relative a larger diameter can be done, the main focus of the relative telescope diameter is about 15-125, even greater, Wang DC, inter Newton Telescope, the tube is longer than the system is much shorter focal length, coupled with the main mirror is only one apparent need for processing, which greatly reduces cost and manufacturing difficulties, there is currently greater than 134 meters diameter optical telescopes are all reflecting telescope.

反射望远镜的相对口径可以做得较大，主焦点式反射望远镜的相对口径约为15—125，甚至更大，而且除牛顿望DC远镜外，镜筒的长度比系统的焦距要短得多，加上主镜只有一个表面需要加工，这就大大降低了造价和制造的困难，因此目前口径大于134米的光学望远镜全部是反射望远镜。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。