— Is it my age ______ the boss minds?—I’m afraid so. He will consider _____ necessary to have an experienced assistant.

It was in time of danger ________ he made the final decision ________ they should send more doctors there.

It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it．

 It is not where you graduated but ________ you have the ability to work out problems ________ counts.

It is the film _______ director is Steven Spielberg _______ attracts quite a few viewers throughout the world.