giải thích giúp em nữa ạ !!
16. At that time they ____ very hard for the new project.
A. are working B. is working C. work D. were working
17. When we were out yesterday I suddenly remembered that I _____ the gas stove so I came back home.
A. didn’t turn off B. had not turned off C. not turned off D. wouldn’t have turned off
18. The police woman suggested the man ______ the gun and they could have a talk together.
A. drop B. to drop C. dropped D. dropping
