Depressant drugs ________ historically have been known to be addictive are called narcotics.

If Americans ate fewer foods with sugar and salt, their general health ________ better.

At Woolworth's first five-and-ten-cent store, ________ more than a dime.

________ the end of the Ice Age around 8000 B.C., mammoths became extinct.

There are two basic kinds of air compressors, reciprocating and ________

Somerset Maugham, a novelist, ________ about a restless man's quest for inner understanding in The Razor's Edge.

________, the jaguar used to roam freely in the southwestern United States.

When linguists encounter a new language, ________ work to identify all of the sounds it contains.

Air ________ the carbon dioxide necessary for photosynthesis enters leaves through tiny surface openings.

George did not do well in the class because ________.