但是，為了創造歷史，加加林當時接受的是一個危險的挑戰，需要極大的勇氣。

但是，為了創造歷史，加加林當時接受的是一個危險的挑戰，需要極大的勇氣。

Results (English) 1:

However, in order to make history, Gagarin accepted a dangerous challenge and required great courage.

Results (English) 2:

But in order to make history, Gagarin was faced with a dangerous challenge that required great courage.

Results (English) 3:

However, in order to make history, Gagarin accepted a dangerous challenge at that time, which required great courage.