【简答题】有一个开普勒望远镜,物镜焦距为300mm,目镜焦距为30mm,中间加入一个由两块透镜组成的- x 转像系统,透镜焦距分别为200mm和300mm,间隔为250mm。该系统的物方视场角2ω=4°,在物镜的像方焦面上有一场镜,在目镜的物方焦平面上有一分划板,物镜的通光口径为60mm,是系统的入瞳。设所有的透镜均是薄透镜,求: (1)系统的像方视场角。 (2)场镜的直径和分划板的直径。 (3)如果在第1...
【单选题】()是指个人或集团,为了实现某种政治目的或改变某种政治进程与格局、运用暴力或威胁手段,蓄意制造恐慌气氛的行为
【简答题】What’s the meaning of “emotionally drained and exhausted” in “ I called on my faithful friends to help make it a merry and festive occasion, ignoring the fact that most of them were emotionally draine...
【单选题】下列选项中,正确说明物质和运动关系的是( )
【单选题】TCP/IP体系结构中与OSI参考模型的的1.2层对应的是哪一层
【单选题】what’s the secret to dress right?
A.
Master the fashion and dress the fashionable wearing
B.
Dress yourself according to the time , occasion, and place
C.
Wear the comfortable clothes
D.
white shirt for gentlemen, beautiful dress for ladies.
【判断题】现浇钢筋混凝土肋梁楼板主要由板、次梁、主梁组成。主梁的跨度一般是5~9m,最大也可以达到12m,次梁比主梁的截面高度小,跨度一般是4~6m,板的跨度一般是1.7~2.5m。