The strange keyes on the old pianos were curiosityies and gave the instruments charming qualitys. which underlined word is spelled correctly?  

Pianos

Explanation:

The word that is spelled correctly in this sentence is "pianos," as this is the plural of "piano." However, the rest of the words are misspelled. "Keys," "curiosities," and "qualities" would be the correct spelling of these words. It is easy to misspell words we do not know. Because of this, it is always useful to have a dictionary available when writing.

i used to know but i learned it a long time ago sorry

explanation:

comfortable

explanation:

one type of the adjectives is predicate adjective. a predicate adjective is an adjective which follows a linking verb and modifies or refers back to the main subject of that linking verb.

it usually is used just before the noun it modies.

here in this example:

'penguins seem comfortable in the coolest habitats', comfortable is the predicate adjective which follows the linking verb 'seem' and modifies the noun.