SAM...TO CHANGE A LIGHT BULB WHEN HE...AND...A. WAS TRYING-SLIPPED...

17. - Tổng hợp các dạng bài cho ôn thi THPT Quốc gia môn tiếng Anh
Tiếng Anh Tổng hợp các dạng bài cho ôn thi THPT Quốc gia môn tiếng Anh
17. Sam...to change a light bulb when he...and...A. was trying-slipped- fell B. tried- was slipping- fallingC. had been trying- slipped- was falling D. has tried- slips- falls