Questions & Answers about Ten proces trwa długo.
Because proces is a masculine singular noun in the nominative case, and the demonstrative must agree with it.
Polish this changes form depending on gender:
So:
- ten proces = this process
- not ta proces
- not to proces
In Polish, many nouns ending in a consonant are masculine, and proces ends in -s.
So learners will usually recognize proces as a masculine noun. In this sentence, it is also the subject, so it appears in the nominative singular form: proces.