Many things that were once considered useful and _____, for example, tobacco, is now thought harmful.

Letters to the editor must carry the writer’s full name, which indicates that writers are _____for what they say．

---It’s ___to rain. ---Let’s get the work ___before the rain comes.

It was ________ the trouble to explain a job fully to new employees.

—Are you pleased with what he has done?—It couldn’t be____. Why didn’t he put more effort into his work?