3 sentences

1. 我们必须抓住工作的纲。

   wǒ​men bì​xū zhuā​zhù gōng​zuò de gāng.

   We must grasp the key link of our work.

   Source: Dong Chinese Dictionary

2. 渔夫抓住了渔网的网纲。

   yú​fū zhuā​zhù le yú​wǎng de wǎng gāng.

   The fisherman grabbed the headrope of the fishing net.

   Source: Dong Chinese Dictionary

3. 学生们需要记住不同动物在生物学上所属的纲。

   xué​sheng men xū​yào jì​zhu bù​tóng dòng​wù zài shēng​wù​xué shàng suǒ​shǔ de gāng.

   Students need to memorize the biological classes to which different animals belong.

   Source: Dong Chinese Dictionary