Principas in English:

I finally understand the basic principles of calculus.

the key principles

I have amongst my relatives, a single one who sincerely lives righteously, has strict principles and pursues an ideal, but all my other relatives speak ill and make fun of him.

Those are my principles, and if you don't like them... well, I have others.

The fundamental principles of classical mechanics were laid down by Galileo and Newton in the 16th and 17th centuries.

The basic principles of grammar are not so difficult.

These rights and freedoms may in no case be exercised contrary to the purposes and principles of the United Nations.

Some people do not have a consistent set of principles; they just adopt whatever principles benefit them at the moment.

Advocates of capitalism are very apt to appeal to the sacred principles of liberty, which are embodied in one maxim: The fortunate must not be restrained in the exercise of tyranny over the unfortunate.

Repairing a broken radio I realise over again that I don't have an understanding of the operating principles of circuitry.

The theory of games shows that what we name "moral principles" are no other than the strategy elements enabling the group to optimise its survival. Men like to dress their eagerness under the guise of charity.

Honesty and truth are essential principles we have been learning since childhood.

In the principles of love, quick disappointments are usually described as remedies.