I know English well.

我精通英语。

youdao

I know it's difficult to master English well.

我知道学好英语不容易。

youdao

I don't know how to learn English well. I hope you can give me some advice.

我不懂得怎样学好英语。我希望你可以给我一些建议。

youdao

As far as I know -- I know of no exception, although someone may well be able to produce one no original poem in English had ever been published with line numbers in the margin in its very first printing.

就我所知，无一例外，尽管有些人能很好的制作出摹本,但英语原版诗歌从不在首次印刷的时候,把行数印在页边空白处。

耶鲁公开课 - 弥尔顿课程节选

I know you can say it easily. I know you can speak well and write well in English. Keep it up!

相信你很快就能掌握的。你的口语跟写作都会很棒的。再接再厉！

I'd better 课堂 - SpeakingMax英语口语达人

I know you're ready to speak English well.

我相信你已准备好说一口漂亮的英语了。

I'm ready to 课堂 - SpeakingMax英语口语达人