.THEY………..FOR 3 HOURS WHEN THE STORM SUDDENLY BROKE.A.HAD BEEN RUNNI...

4. - BAI KIEM TRA 1 TIET SO 1 UNIT1UNIT3 E12
BAI KIEM TRA 1 TIET SO 1 UNIT1UNIT3 E12

4..They………..for 3 hours when the storm suddenly broke.

a.had been running

b.have been running c.are running d.will be running