Sabay is the best learner’s site, because at the top of each article is a switch for adding spaces to the Khmer, very handy for separating words!
http://news.sabay.com.kh/
this site has some examples of translated KM-EN sentences at the bottom
https://glosbe.com/km/en/%E1%9E%86%E1%9F%92%E1%9E%93%E1%9E%B6%E1%9F%86%E1%9E%84
don’t forget to install myVocabu if you want to translate any Khmer into your language (select Khmer text in page and press whichever Hotkey you set up in myVocabu settings – I prefer SHIFT key for this)