序数词：third.（表示第三）基数词：three.（表示三个）例句：We waited three months before going back to see the specialist. 我们等了3个月才回去见那位专家。

Our team won three matches, drew one and lost two. 我们队胜了三局，和了一局，败了两局。I studied in the same school with them for three years. 我和他们同过3年学。Three characters are missing in this line. 这一行里脱了3个字。He had three tries and failed each time. 他试了三回，每回都失败了。