THEY SHOULD CLEAN THEIR TEETH TWICE A DAY. THEIR TEETH SHOUND BE CL...

3. - DE KIEM TRA 15 BAI 6 HOC KY 2 CO DAP AN SACH 10 MOI
DE KIEM TRA 15 BAI 6 HOC KY 2 CO DAP AN SACH 10 MOI

3.They should clean their teeth twice a day.

Their teeth shound be cleaned twice a day.