All of the doctors have worked for a long time, but ________ of them stop to have a rest.

Helen was so careless that she made _______ mistakes in her math exam.

I don't think _________ possible to master a foreign language without much memory work. 

--Have you got _______ ready for the school trip？  ---Not yet. We still have _______ to do.

The US/UK war against Iraq and the suffering _____ caused have become a big concern all over the world.