翻译我现在必须好好学习，长大才能当好英语老师。

I must work hard, and I will be a good teacher.

我觉得这个比较符合六年级的

I have to study very hard now in order to be an English teacher in the future.

看你当拿个级别的老师了 小学 初中 主要看你的 英语功底和教学经验 翻译是必须的但不重要 重要的是你所学的能讲出来 说实话小学初中 你的翻译一般就可以了 真正用到的是你会教 多练习讲课

I have to learn now, can grow up to be a good English teacher

I must do well in my study in order to become a competent English teacher in the future.

解释:
do well in sth:在某方面做的好
in order to :为了.../为了达到...的目标
competent :好的,称职的,胜任的

i must study hard ,so i can to be a good English teacher in the future