---Did you notice someone enter the classroom just now?---Sorry, I didn’t. I _____ my lessons at that time.
Everyone is supposed ________ a seat belt in the car. A. wearing B. to be worn D.wear D. to wear
The bridge _____ by the farmers themselves in 1982.
There are many tall buildings on ____ sides of the street .
The president _____ all people _____ our environment.
At last, Lucy make the baby ____ and the baby began to laugh.