The chairman thought _________ necessary to invite Professor Smith to speak at the meeting.
—Where is our English teacher?—She is in the classroom, _____ the exercises _________ the students have done at home.
Tom does speak Chinese well, but his reading and writing skills leave much _______.
To get an education, _______.
That gas pipeline project, _____in July 2002 and__________in 2005, will be China’s longest gas pipeline in history.
We saw new houses_____wherever we went on our visit.