People are advised to be _____ towards the health concerns of their dear ones while burning firecrackers to celebrate the festival, for they contain harmful chemicals．

 The waters of the lake were so     that it looked like glass . 

As the economy is getting better and better, there are more and more jobs _____.

 How cold it is! We’ve never had ______ this winter.

The work was difficult, but Tom’s ____expression showed that he would finish it in time.