The lack of eco-friendly habits among the public is thought to be a major ____ of global climate change.
The police tried to get some clues from the suspect, but he remained______.
________by the advances in technology, many farmers have set up wind farms on their land.
Not until I began to work ____ how much time I had wasted.
It was_______ that they went for a drive in the countryside.
Simon made a big bamboo box the little sick bird till it could fly.