One of the main __________ of the summit was “sustainable development”,or the question how we can continue developing the world without damaging the environment.

 The need for an operation，especially an immediate operation， almost always comes as a ______ to the patient and his family. 

Bob has learned a lot from his _______ of working in different gyms and is now an expert on all kinds of _______. 

England is rather short of arable land , so it is absolutely dependent upon other countries for her food __________．

My morning _______includes jogging in the park and reading newspapers over breakfast.