He started to learn English in 1990 and in the years ________ he kept on using it in his work.
I don’t understand what the teacher means, but I’ve got ____ rough idea of ____ plan.
I need time to _______ on what the teacher taught in class.
Many students are not __________ the harm of staying up late into the night, which causes damage to their health.
Please post this letter in the post office nearby, and __________, I will get two tickets in the train station.
. A clean environment can help the city bid for the Olympics, ________ in turn will promote its economic development.