So far we have done a lot to build a low-carbon economy, but it is idealWe have to work stillharder.[ ]

It was only after he had read the papers ________ Mr.Gross realized the task before him was extremely difficult to complete. (2013·大纲全国，30)

He could see the tall chimneys of the factory________.

Plants and trees need water to grow; ______, friendship needs our heart and passion to develop.

Our team won the basketball final today! -_______.