1 . The question discussed at the meeting was ________ it was worth trying. (用适当的词填空)

2 . I’m a bit sleepy, it’s________ I was up all night. (用适当的词填空)

3 . The trouble is_______I lost the key to my room. (用适当的词填空)

4 . My difficulty is ________ I really don’t know how to communicate with her. (用适当的词填空)

5 . If you often feel tired and can’t focus your attention, that is ________ you have to stop working too hard and to have a rest. (用适当的词填空)

6 . Air pollution is ________ most Chinese people are concerned about nowadays, because their health is being threatened. (用适当的词填空)

7 . The most pleasant thing of the rainy season is __________ one can be entirely free from dust.

8 . One of his first findings was ___________articles in the science section were much more likely to make the list than non-science articles. (用适当的词填空)

9 . The second reason is _________people are living longer. A child born in the US today has a very realistic chance of living beyond 100 and needs to plan accordingly. (用适当的词填空)

10 . The truth is ___________we are lucky enough to have clean water whenever we want, but this is not the case for many people around the world. (用适当的词填空)