Each member country of WTO must _____ its laws and regulations and compete on the principle of fairness and co-operation.
Noise is unpleasant, _____ when you are trying to sleep.
So hard-working _____ that he sets a good example to all the other classmates.
With more and more forests _____, many animals are facing the danger of dying out.
As we all know, China is a developing country, _____ attracting more and more foreigners.
The beautiful town, _____ we spent our summer vacation last year , lies at the foot of a mountain.