你要相信自己一定能通过考试。

Nǐ yào xiāngxìn zìjǐ yídìng néng tōngguò kǎoshì.

You must believe that you can definitely pass the exam.

我相信只要努力，你一定能学好中文。

Wǒ xiāngxìn zhǐyào nǔlì, nǐ yídìng néng xuéhǎo Zhōngwén.

I believe that as long as you work hard, you will definitely learn Chinese well.

你要相信自己，一定可以学好中文。

Nǐ yào xiāngxìn zìjǐ, yídìng kěyǐ xuéhǎo Zhōngwén.

You must believe in yourself; you can definitely learn Chinese well.