3 sentences

1. 由于赛季表现不佳，这支球队不幸降级了。

   yóu​yú sài​jì biǎo​xiàn bù jiā, zhè zhī qiú​duì bù​xìng jiàng​jí le.

   The team was unfortunately relegated due to poor performance during the season.

   Source: Dong Chinese Dictionary

2. 他因违反公司规定被从经理降级为普通员工。

   tā yīn wéi​fǎn gōng​sī guī​dìng bèi cóng jīng​lǐ jiàng​jí wéi pǔ​tōng yuán​gōng.

   He was demoted from manager to a regular employee for violating company regulations.

   Source: Dong Chinese Dictionary

3. 信用评级机构将该国的信用等级从AAA降级为AA。

   xìn​yòng​píng​jí jī​gòu jiāng gāi guó de xìn​yòng​děng​jí cóngAAA jiàng​jí wéiAA.

   Credit rating agencies downgraded the country's credit rating from AAA to AA.

   Source: Dong Chinese Dictionary