One thing that most organically grown food products seem to have in common is that they cost more than ________ grown foods.

A model or an experiment in a science class can help us see things which would_______ remain hidden.

—You don’t seem to be quite yourself today. What’s wrong? —Oh, I’m suffering from a cold. Nothing serious, _____. 

Having been told ________ where he lived, I had no difficulty in finding Peter’s address.

Kevin was not good at Chinese at first. After two months in China, _____, he made great progress.