3 sentences

1. 在这个方程式中，x是一个变量。

   zài zhè​ge fāng​chéng​shì zhōng,x shì yī gè biàn​liàng.

   In this equation, 'x' is a variable.

   Source: Dong Chinese Dictionary

2. 如果条件不成立，布尔变量的值就是假。

   rú​guǒ tiáo​jiàn bù chéng​lì, Bù'ěr biàn​liàng de zhí jiù shì jiǎ.

   If the condition is not met, the value of the boolean variable is false.

   Source: Dong Chinese Dictionary

3. 在编写代码之前，你需要先确定变量的类型。

   zài biān​xiě dài​mǎ zhī​qián, nǐ xū​yào xiān què​dìng biàn​liàng de lèi​xíng.

   Before writing code, you need to determine the types of the variables.

   Source: Dong Chinese Dictionary