WE OUGHT TO TRY CLEAN OUR TEETH ...A. ONCE A DAY B. AT LEAST TWICE...

4. - TEST 1 CHUYEN ANH G 9 2010
TEST 1 CHUYEN ANH G 9 2010

4. We ought to try clean our teeth ...

A. once a day B. at least twice a day

C. between meals D. before breakfast.