According to my Russian learning book, short adjectives are formed by taking the root of the adjective and adding:
- -ø for male (null ending)
- -a for female
- -o for neutral
Thus, the adjective красивый, -ая, -ое will give the following three short adjectives: красив, красива, красиво.
My book also mentions that short adjectives are often used after так and как.
My question is: in the expression Как хорошо!, what is the word class of the word хорошо, and why? I’ve heard many times that it is an adverb in this case, but what I see in my learning book would lead me to say that it’s a short adjective (also because one can say Какой хороший, which is then the long form).