People who are infected with HIV are often looked down upon because social _____ against the disease runs so deep.

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

 After working all the day, he was so tired that he was in no _____ to go to the party with us.

There are ten＿＿＿teachers and two hundred＿＿＿students in the school．

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