Unless ______, the boy wouldn’t have admitted that it was he who broke the video.

Don’t touch your eyes, nose and mouth, because they aren’t covered by skin and can ________ the virus easily.

Readers are required to _________ the rules of the library and mind their manners.

You’d better put things back______. Otherwise, it will be difficult to find them.

Sam _____ some knowledge of the computer just by watching others working on it. 

The suggestion, ____ by the locals, proved to be a very constructive one.

Sam _____ some knowledge of the computer just by watching others working on it. 

Father is     us a meal . We may wash our hands and     the meal.

Mr. Brown’s condition looks very serious and it is doubtful if he will ________.

Helen has ____French and can speak fluently after a short stay with her aunt in Paris.