Mary ______ all the housework, she dropped herself into the sofa, sighing with relief.

You have no idea how she finished the relay race________ her foot wounded so much.

Mary often stays up, reviewing her lessons, books___ all over the desk.

With efforts _______ conservation, we may believe that people enjoy a healthy life without the environment around them ________. 

Many strange new means of transport have been developed in our century, the strangest of _______ being perhaps the hovercraft(气垫船).