Time is________, so we should not waste it. [ ]

— Look at the sign on the right.— Oh, smoking ____ here. [ ]

More than a quarter of the energy _____in the United States goes to moving people and goods from one place to another[ ]

The cat made a lot of noise last night. It ______________ a baby crying.

_ is surprising to us is that Tom, for ______ English was once boring, can speak English fluently as though he were a native speaker.