送交者: year2226 于 2010-08-11, 19:02:21:

回答: SR-71 and M-21 were developed the same time by the same team. 由 steven 于 2010-08-11, 18:44:38:

• D-71 was too complicated for its time. - steven (45 bytes) 2010-08-11, 20:05:48 (473751)

加跟贴