The woman sold the eggs ________ seven dollars and they were sold________half price.

The purpose of the article is to draw public attention ______ the problem.

The story is so amusing that it kept the children laughing for minutes______

While in London，we paid a visit to the hospital founded ________ Florence Nightingale.

At the railway station，he waved goodbye to his friend until the train was ________.

．She was told to wear flat shoes ________ her back problem.

We’d better discuss everything ________ before we work out the plan.