________(由于电梯故障), everyone had to walk.
The rise in food prices is largely a result of
The abundance of food may be disastrous to farmers because of
According to the author, except global warming and privatization of water,______is also responsible for fresh water shortage.
She looked at her five children with (evidence) ______pride on her face.
I can not help (wonder) ______whether the doctor will come in time.