THE POLLUTION PROBLEMS HAVE BEEN DISCUSSED (BY THE STUDENTS) SINCE LAST WEEK

14. - GIÁN ÁN BAI TAP VE CHUYEN DE BI DONG(CO DAP AN)
GIÁN ÁN BAI TAP VE CHUYEN DE BI DONG(CO DAP AN)

14.The pollution problems have been discussed (by the students) since last week.