He is not easy-going, but his trust in his friends will last forever once _______.
----Whose advice do you think I should take? ----________.
I know a little bit about the city as I __________ there for one year in my youth.
Leaves are found _______ all kinds of trees, but they differ greatly ________ size and shape.
To save class time, our teacher has ________ students do half of the exercises in class and complete the other half for our homework.
Now an increasing number of middle school students go abroad for further study at their own ________, trying hard to realize their dreams.