It is believed that high achievers work toward personal standards of excellence ______ material rewards.

We didn’t know you were in trouble at that time,_____ we would have given you a hand.

  ______ began our new lesson.

As is known to all, the newly learnt words will soon be forgotten unless_____ used in everyday communication.

Life is stressful, and complaining may be considered by many as an extension of being________normal.