What does the word keen mean in the sentence below?

The bat has a keen sense of hearing.

the publisher is the publishing date is the author is

united states of america . . 1942 . . t. s. eliot

houghton mifflin company . . 2002 . . gregory stock

houghton mifflin company . . 1942 . . t. s. eliot

houghton mifflin company . . 2002 . . robert overholtzer

the best sentence that shows the best placement for the modifier "on the ice" is the one which contains it in the end of the sentence or in its beggining followed by a comma, that indicates it works as adverbial, dislocated in the sentence.

the girl promptly slid on her rollers on the ice.

on the ice, the girl promptly slid on her rollers.

your answers are correct.