He considered __________ the book, which was considered __________ a great help in his study.
I’m going to write articles and send _________ magazines and newspapers.
David is going to travel _________ the world.
Anna wants to study English and she’s going to study economics(经济)________.
The Greens are going to ________ Dalian next year.
My aunt is going to retire(退休)___________.