谢谢你的评论
那个飞机的速度应该是1000KM/H, 我短路了:o
我先构思的时候也想着让步来着,写着写着就给忘了...
那个第三段这样改可以么,
Finally, the advancement of software indeed lends a significant help for us to handle stuffs which are used to regard as complex work with less efforts, though they seems elaborate superficially, CAD is a typical example. Admittedly learning how to operate a certain software is not a relax activity, after understand its principle we can use it conveniently realize our purpose. engineers used to draught the drawings with a long period of time and they must be pretty careful to avoid serious mistakes because draw it all again is a complicated and tore work, but with the CAD, we don’t need to worry this problem any more. We are able to eliminate what we are not satisfied conveniently. Further, the software case is not rare. So, we could easily achieve our goals nowadays.