Question

英语句子有语法错误吗？

He knows he can never change back to the original himself again.

However, beneath his pretend appearance, he is quite evil. Because he has to keep good manners in front of the people, so he holds and constrains his evil desire constantly.

Answer 1

整体表达还是非常流畅的，个别措辞不准确，比如original改成initial较好。however连词用的不很恰当，意思不很清晰，不知道你本来想如何表达。
1，in front of the people，加上the，表示“人民，民众”，如果表示“人们”一般后面加上定语比较合适，例如：in front of the people you care about，你关心的人。
因此建议：in front of people
2，because和so不能连用，把第二句的so去掉，因为两个都是连词，一起用，就不是完整的一句话了。

Answer 2

在线翻译的手笔吧。典型的中式英语。。。 。。。发份中文过来瞧瞧。

Answer 3

初中生觉得，好像没有错误吧