16.-What about going abroad?-Great, but I never expected______a chance for me before.
--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.
He is always______fault with other people though he doesn’t do his own work properly.