冷酷な

い-adjectives (like 冷酷な) can directly modify a noun. For example, 冷酷な人 (reikokuna hito) means 'a cruel person.'

彼は冷酷な人だ。 (Kare wa reikokuna hito da.) He is a cruel person.

To use い-adjectives as an adverb, you change the ending to -く (ku) and add a verb. For 冷酷な, it becomes 冷酷に (reikoku ni). For example, 冷酷に扱う (reikoku ni atsukau) means 'to treat cruelly.'

彼らはその動物を冷酷に扱った。 (Karera wa sono dōbutsu o reikoku ni atsukatta.) They treated that animal cruelly.

When comparing two things with い-adjectives, you can use より (yori) after the item being compared against. For example, Aより冷酷なB (A yori reikokuna B) means 'B is crueler than A.'

彼の兄は彼より冷酷な性格だ。 (Kare no ani wa kare yori reikokuna seikaku da.) His older brother has a crueler personality than him.

To express something 'is not' with an い-adjective, you replace the final な with ではない (de wa nai). For example, 冷酷ではない (reikoku de wa nai) means 'not cruel.'

彼は見た目ほど冷酷ではない。 (Kare wa mitame hodo reikoku de wa nai.) He is not as cruel as he looks.

You can combine い-adjectives using て (te) form to list qualities. For 冷酷な, you use で (de). For example, 冷酷で賢い (reikoku de kashikoi) means 'cruel and smart.'

彼は冷酷で賢いリーダーだ。 (Kare wa reikoku de kashikoi rīdā da.) He is a cruel and smart leader.