Air pollution is getting more and more serious, so we must take action it is too late.
He managed to reach the summit of his career, but it was at the _________ of his health.
As is well known, the brain performs a very important _______, which controls the nerve system of the body.
_____ is a good form of exercise for both young and old.
“May I take your order now?” “We’d like three black _______ and two green _______.”
She raised her finger to her lips as _____ for silence.