简述直线对于一个投影面的投影特性。
参考答案:
当直线平行于投影面时,其投影反映真实长度;
当直线垂直于投影面时,其投影积聚成一点;
当直线倾斜于投影面时,其投影变短。
请以“有一种力量,让我泪流满面”为题,写一篇不少于800字的记叙文。
Disappointed, I was about to leave________something occurred, which________my attention. [ ]
A. while: paid
B. and: got
C. before: drew
D. when: attracted