الخطوة 1اختر الخيار الصحيح
الخطوة 2أضف التدريبات التي تعجبك إلى المفضلة
Coward (= one without courage) is the noun. The adjective is cowardly.
Others isn't an adjective but a pronoun. The adjective is other (without the s) We can say: The others aren't here, omitting the noun boys.
Hot is an adjective only, and we can't use it as a noun. The noun is heat.
The adjective is open. The past participle is opened: Somebody has opened all the windows.