YOU MUST (KEEPING, ARE KEEPING, KEEP,IS KEEPING) YOUR CLASSROOM CLE...

3) - KIEM TRA 1 TIET ANH 8BAI SO 2HK IICO MA TRAN
KIEM TRA 1 TIET ANH 8BAI SO 2HK IICO MA TRAN

3) You must (keeping, are keeping, keep,is keeping) your classroom clean and tidy