—Jack failed the driving test again.—The question is_____ we can help him avoid making the same mistake.
She's aiming ________ a scholarship. That is why she has been focusing her mind ________ her work.
Once you ______ the habit of smoking, it is hard to quit.
It's high time that you ________ even harder at your lessons as the exam is around the corner.
The center, dealing with children_______ to computer games, has achieved great success.
—How I wish I had studied harder when I was in senior school! —If you had,you ________ a university student now.