If there is pollution, the air in our city will be dirtier.

Their relationship，______ onyears of open communication with each other，will last.

hoped that you would be able tovisit us, but you _____

Why do you look so tired today —It is because I _______ late last night to prepare for the final exam tomorrow.

e the drowning child, the boy plunged into the icywater without hesitation, ____ his own safety