用表格中所给词的适当形式填空

　　Yang Liwei always dreamed of ___1___ through the air while he was growing up. In 1987, his dream came true at last. Over ten years later, Yang Liwei was ___2___ to start training for a space mission. Thirteen other pilots were also chosen. This ___3___ was very difficult. At the end, one of these ___4___ would become the first Chinese man to go into space. The training ___5___ five long years. On October 14, 2003, Yang Liwei was told that he was going to be the first taikonaut. He was going to go into space the next day! On that first space mission, Yang Liwei spent 21 hours and 23 minutes in space.

用所给词的适当形式填空，使文章通顺、连贯、合理。