我有一个中文作业是“给实习了3个月的公司写一封感谢信”。我这样写可以吗？

[hoary goblet]

尊敬的明发公司领导及全体员工:

您好！

我叫玲，**是**顺化外国语大学的学生，刚刚在公司完成了三个月的实习。我写这封信是为了感谢公司和全体员工在上次实习**中**对我**的**~~帮我~~**帮助**。

在公司实习的过程我积累了很多实际知识，并且还锻炼了重要的软技能。特别是，我非常感谢华老师的热情指导，她花很多时间指导并帮助我改善自己。在公司的经历将成为我未来职业道路的宝贵财富。

祝愿明发公司不断发展壮大，取得更加辉煌的成绩。祝愿全体员工身体健康，永远快乐。

致以。

[dawn rune]

i would replace all 公司 with 明发 or 明发公司 or 贵公司（which is more formal）
also 永远快乐 sounds a bit off, maybe just 生活快乐

[brisk fulcrum]

我叫玲，顺化外国语大学的学生，刚刚在公司完成了三个月的实习。我写这封信是为了感谢公司和全体员工在上次实习对我帮我。

【我叫玲，是顺化外国语大学的学生，刚刚在贵公司完成了三个月的实习。我写这封信是为了感谢贵公司和全体员工在这次实习中给我的帮助。】

• 上次 means "the previous time", and implies that the most recent internship isn't the only one you have done with them. If you're referring to the most recent internship, that internship is 这次实习, or just 实习 if this is the first time you've worked with them.
• As diff said, since this is a formal letter, either write out the company's name in full, or use 贵公司. 公司 is only used to refer to a company when you are part of that company, not when you've left it.

在公司实习的过程我积累了很多实际知识，并且还锻炼了重要的软技能。
【在公司实习的过程，我积累了很多实际的知识，也培养了重要的软技能。
特别是，我非常感谢华老师的热情指导，她花很多时间指导并帮助我改善自己。
【我特别要感谢华老师热情的指导，因为她花了很多时间来指导我改善我自己。】
在公司的经历将成为我未来职业道路的宝贵财富。
【我相信我在贵公司累积的经验将会是以后职场上的宝贵财富。】

• 职场 is the word you want to mean "career".

祝愿明发公司不断发展壮大，取得更加辉煌的成绩。祝愿全体员工身体健康，永远快乐。
【祝愿明发公司不断卓越成长，取得更加辉煌的业绩。祝愿全体员工身体健康，生活快乐。】

• As diff pointed out, we don't wish that people live "happily ever after" (永远快乐), we just wish that they have a happy life (生活快乐).
• While 成绩 does mean "accomplishments", 业绩 is more often used to talk about performance in a commercial setting: https://en.wiktionary.org/wiki/業績

[sacred vigil]

Actually, I feel like this kind of wish sounds too formal. I want it to sound simpler and more polite, but I haven't found the right words to replace it yet TT

[sacred vigil]

Chinese grammar is quite difficult for me to apply because it's the opposite of my native language's grammar Thank you for helping me

[brisk fulcrum]

Actually, I feel like this kind of wish sounds too formal. I want it to sound simpler and more polite, but I haven't found the right words to replace it yet TT
生活(快乐/愉快) is a simple wish that's frequently used and pretty polite without being too formal. However, nobody uses 永远快乐, because we don't live in fairy tales.

[sacred vigil]

-I thought 上次 only referred to this internship. Thank you for helping me distinguish it.
-I want to show the meaning of "career path", is this word “职场上” okay?
-发展壮大 meaning "broad development", not this word?

[brisk fulcrum]

I want to show the meaning of "career path", is this word “职场上” okay?
职场上 means "in (my) career", and so 我相信我在贵公司累积的经验将会是以后职场上的宝贵财富 just means "I believe the experience I've gained at your company will be a precious treasure in my future career." There is no need to translate "path" here.

[sacred vigil]

So I should fix it as the other friend answered, 生活快乐 :O?

[brisk fulcrum]

So I should fix it as the other friend answered, 生活快乐
That's what I suggested as well. This is the saying that's actually used very often.

[sacred vigil]

I see, thank you so much! I'm not good at turning Chinese words into a complete sentence. The grammar and vocabulary are quite difficult to learn. I really admire those who are good at and fluent in Chinese.