He is __________ unusual inventor and he invented _________ useful invention.A. a; an B. a; a C. an; an D, an; a
—_____ you please play tennis with me? —Sorry, I _____.
Smoking is bad for your health. You should.
Aron water five days later.
This is______difficult problem that few students can work it out.
.He lives_______in the______village, but he is never_______.