.that is
[用作插入语]那就是，即，换句话说，就是说
He is a good student; that is, he gets good grades in school. 他是个好学生，就是说，他在学校成绩很好。
Arabic is written in the opposite direction to English, that is, from right to left. 阿拉伯文的书写方向与英文相反，即从右到左。
[注意：在书面语中，拉丁语 id est 的简写式 i.e. 往往代替 that is; 但在口语中 i.e. 常读作 that is]
