长城是在不同的朝代不断修建和加固的。

Chángchéng shì zài bùtóng de cháodài bùduàn xiūjiàn hé jiāgù de.

The Great Wall was built and reinforced continuously in different dynasties.

老师让我们按时间顺序，把中国主要的朝代写在时间轴上。

Lǎoshī ràng wǒmen àn shíjiān shùnxù, bǎ Zhōngguó zhǔyào de cháodài xiě zài shíjiānzhóu shàng.

The teacher asked us to write the main Chinese dynasties on a timeline in chronological order.

每个朝代都有自己的代表性建筑和艺术风格。

Měi gè cháodài dōu yǒu zìjǐ de dàibiǎoxìng jiànzhù hé yìshù fēnggé.

Each dynasty has its own representative architecture and artistic style.