科学家们正在研究如何成为优秀的星球改造者，让火星适合人类居住。

Scientists are studying how to become skilled ___terraformers to make Mars habitable for humans.

这部科幻电影中的行星改造者将火星的大气层变得适合人类呼吸。

In the sci-fi movie, the ___terraformers made Mars' atmosphere breathable for humans.