They will start their project ____at helping the poor children to be educated in China's west.
Finding the ______look on the student’ s face, the professor felt _____about his explanation.
The ancient village, ______ they visited during a recent trip, is the only tourist attraction ______ is well protected without any damage.
The director is going on business next week and the department will be left ______Jack.
During adolescence--- ______time of life between child and adult, teenagers want to be __________part of the group.
—— Do you think you can repair this machine without help?—— _________. This is not the first time for me to do so.