

どうぞ、中へ入ってください。
寒いから、早く中へ入ろう。
犬は家の中へ入りませんでした。
"なかへ(中へ)" is in the lesson "Directions" (Level 19), along with 12 other useful words. LinDuo has 180 topic lessons like this one, 2,379 words in total. Every word has an illustration, a transcription and pronunciation in a female and a male voice. Just 10–15 minutes a day is enough to learn them all. Free, and works offline.