They arrived at a farmhouse,in front of ________ sat a small boy.
According to the survey, two thirds of the area__________covered by trees now and 90% of the population__________contributions to the Greening Project in the city.
He asked me__________with me.
It is time for class. Will you please get the blackboard__________?
This is the biggest lab__________we have ever built in our university.
He is__________as a leader but he hasn’t__________in teaching.