Although everything seems to have been taken into consideration, accident can happen when the astronauts walk in space.
A. /; the
B. an; the
C. the; the
D. an; /
网友回答
A. /; the
B. an; the
C. the; the
(答案→)D. an; /
解析：考查冠词。第一空填不定冠词表泛指，第二空space“太空”前不加冠词，故选D项。