Plans have been proposed ______ the largest dam in the world to be built along the Congo river.
Some students have trouble _______grammar while others have difficulty —___ new words.
We were going out for a walk ________ it began to rain.
— What did Tina say just now?— She asked ____ this summer holiday.
Bill’s fully ____ from his heart disease. He is very happy.
While____the dog,you should take care not to____.Otherwise,it may be dangerous to strangers.