cosmonaut

例句：

1. 1.The astronaut was the first to set foot on the moon.
   这位宇航员是第一个踏上月球的人。
2. 2.He has been living in space for several years now.
   他已经在太空生活了好几年了。
3. 3. Cosmonauts are trained to survive in extreme conditions.
   宇航员们接受过在极端条件下生存的训练。