The boy was so tired that he fell asleep ______ his mother could take off his clothes.
Every possible means ______to prevent the air pollution, but the sky is still not clear.
I have no _______ to the plan, so long as it would not cost too much.
Don’t use words, expressions or phrases _____ only to people with specific knowledge.
Scientists still wonder ______ cloning will help or harm us and _____ it is leading us.
After the National Entrance Examination the students will have an anxious couple of weeks _____ for the results.