During the past ten years, there have been _____ changes in the country.
During the past ten years, there have been \_\_\_\__ changes in the country.
过去
It’s time that we _____ to take care of our own house.
It’s time that we \_\_\_\__ to take care of our own house.
After driving for twenty miles, he suddenly realized that he has been driving in the wrong direction.
After driving for twenty miles, he suddenly realized that he has been driving in the wrong direction.
The children _____ happily in the classroom when the teacher came in.
The children \_\_\_\__ happily in the classroom when the teacher came in.
In the road accident the other day three people _____，including the driver.
In the road accident the other day three people \_\_\_\__，including the driver.
He would be studying at the university now if he _____ the entrance examination.
He would be studying at the university now if he \_\_\_\__ the entrance examination.