They are sweating all over. They ______ in the field.A．may beB．must have been workingC．cou

They all returned to the village ______ that the danger was over.A．convincingB．convincedC．

They are sure they have all the facts they need to ______ the existence of a black hole.A．

Todays trumpet is similar to its ancestors EXCEPT thatA．they are all hollow tubes.B．they a

"They vault over technical fixes as fast as the hurdles are erected"（Para. 1)probably mean

People all over the world, old and young, men and women, love sports. They do sports for f

Television ads are short ，but they are repeated over and over again _____ the audien