He started to learn English in 1990 and in the years ________ he kept on using it in his work.
I am interested in traveling. It is ______ but ______.
The windows haven’t cleaned for a long time. They need ______.
Our teachers are really ______. They often work in their office far into the night.
Visitors were at the pictures that the guide showed.
His grandparents were born in ______ Qing Dynasty, while he was born in ______ 1920’s.