他们约好周六一起去打篮球。

Tāmen yuēhǎo Zhōuliù yìqǐ qù dǎ lánqiú.

They agreed to go play basketball together on Saturday.

下次有空儿，我们再约出来吃饭。

Xiàcì yǒu kòngr, wǒmen zài yuē chūlái chīfàn.

Next time when we are free, let’s arrange to go out for a meal again.

我已经和同学约好一起去图书馆学习。

Wǒ yǐjīng hé tóngxué yuēhǎo yìqǐ qù túshūguǎn xuéxí.

I have already arranged with my classmates to go study at the library together.