“距离我第一次到达地球的时间已经过去了21年”用英语怎么说？

It has been 21 years since I landed on the Earth for the first time.

I have been living on the Earth for 21 years.

地球是专有名字，earth前面要加定冠词

“距离我第一次到达地球的时间已经过去了21年” - It has already been 21 years since I arrived at Earth.

我已经在地球上生存了21年” - I already lived for 21 years on Earth.

距离我第一次到达地球的时间已经过去了21年

There are 21 years since I firstly arrived at earth.

我已经在地球上生存了21年

I have been alived on earth for 21 years.