

この店は外国のお客さんが多いです。
外国のお菓子を買いました。
外国の服は高いですか。
"がいこく(外国)" is in the lesson "Shopping" (Level 34), along with 13 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.