The cars’ contribution to the greenhouse effect is great．

He made a very positive contribution to the overall success of the project．

All contributions will be gratefully received．

Nothing could be more certain．

What is certain is that every effect must have a cause．

To save more money, you can set aside a certain sum each week．

The government’s argument is that they must first aim to beat inflation．

There are strong arguments for and against capital punishment．

They got into an argument with the referee about his decision．

Over a year passed before the first attempt was made．