—Where did you get to know her? —It was on the farm _________ we worked.
I remembered __________ the door before I left the office, but forgot to turn off the lights.
The manager __________ the workers how to improve the program since 9 am.
In order to find the missing child, villagers __________ all they can over the past five hours.
—I am __________ endless examinations. —Cheer up, David. Keep on until the college entrance examination ends.
The company is making efforts to encourage its workforce to make the switch to __________ means of transportation, such as carpooling or biking to reduce air pollution.