或缺

红薯和木薯的块茎中富含大量可供提取的天然优质淀粉，是食品加工和造纸工业中不可或缺的原料。

hóng shǔ hé mù shǔ de kuài jīng zhōng fù hán dà liàng kě gōng tí qǔ de tiān rán yōu zhì diàn fěn, shì shí pǐn jiā gōng hé zào zhǐ gōng yè zhōng bù kě huò quē de yuán liào.

The tubers of sweet potatoes and cassava are rich in natural high-quality starches that can be extracted and are indispensable raw materials in the food processing and paper industries.

强大的现代化国防力量是维护国家主权、领土完整与和平发展不可或缺的坚强柱石。

qiáng dà de xiàn dài huà guó fáng lì liàng shì wéi hù guó jiā zhǔ quán, lǐng tǔ wán zhěng yǔ hé píng fā zhǎn bù kě huò quē de jiān qiáng zhù shí.

Strong modern national defense force is an indispensable and strong pillar for safeguarding national sovereignty, territorial integrity and peaceful development.

学而不思则罔，思而不学则殆，知行合一亦是青年求学成才不可或缺的重要准则。

xué ér bù sī zé wǎng, sī ér bù xué zé dài, zhī xíng hé yī yì shì qīng nián qiú xué chéng cái bù kě huò quē de zhòng yào zhǔn zé.

If you learn without thinking, you will be in vain; if you think without learning, you will be in danger. The unity of knowledge and action is also an indispensable and important criterion for young people to study and become successful.