They are all very clever, but _______of them could work the problem out.

________ arouses his interest can be found in the school library and that is why he goes there ________ happens.

Both teams were in hard training, ____was willing to lose the game.

The chairman thought       necessary to invite Professor Smith to speak at the meeting.

Use your head; nothing taught by others can have the same effect on you as _________learnedthrough practice.