–How far apart do they live?–_____ I know, they live in the same neighborhood.
Mrs. Black doesn’t believe her son is able to design a digital camera, ________?
--How is_______ going with you? -- So so.
One way to understand thousands of new words is to gain _____ good knowledge of basic word formation.
--Do you know anyone in Paris? --No, I’ll make friends once______ .
The research is so designed that once ______ nothing can be done to change it.