The house built of stone lasts longer than ____ built of wood.

All we have is 24 precious hours a day and therefore we shall waste ______

I think Mrs. Stark could be _______ between 50 and 60 years of age.

The most important thing for Lucy is to find a proper job, ______ in which she can bring her ability and potential into full play．

—Which of these two English books will you borrow?—I’ll borrow ____________ of them because they are very interesting.