On April 12, 1961，27—year—old Yuri Gagarin(尤里.加加林)became the first human to go into space.

On April 12, 1961， 27—year—old Yuri Gagarin(尤里.加加林)became the first human to go into space.
A. the;不填
B. the; the
C. a;不填
D. a; the

A. the;不填B. the; the(答案→)C. a;不填D. a; the解析：冠词用法。由句意：在1961年4月12号，27岁的尤里.加加林成为进入太空的第一人。space作“太空”时一般不用冠词。故选C

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