_____ we were worried about was _______ they could manage to control the pollution.

The most important thing about my job is ______ I help protect ordinary people from the volcano.

________ happens in the world makes us happy and sad by turns. 

—________is it ________ had made our headteacher that angry?— Six of us being late this morning.

The boss refused to sell the car for ________ he thought was not satisfactory.