国庆节的时候，街上到处都是国旗。

Guóqìngjié de shíhou, jiē shàng dàochù dōu shì guóqí.

During National Day, there are national flags everywhere on the streets.

他们在公园里举行了一个简单的庆祝活动。

Tāmen zài gōngyuán lǐ jǔxíng le yí gè jiǎndān de qìngzhù huódòng.

They held a simple celebration event in the park.

为了庆祝他的生日，我们买了一个大蛋糕。

Wèile qìngzhù tā de shēngrì, wǒmen mǎi le yí gè dà dàngāo.

To celebrate his birthday, we bought a big cake.