halons

"After I finished reading the book, I replaced it on the shelf. "

"Be careful not to damage any of the fragile items while unpacking them."

"Gasoline is a hydrocarbon fuel used in many cars. "

"Hydrogen is the simplest chemical element, with only one proton in its atom. "

"Table salt, or sodium chloride, is formed when the metal sodium reacts with chlorine, one of the halogens. "

"The box contained old photographs. "

"She put her books on the table."

"The new recruit was a strong and effective soldier, ready for basic training. "

"By now, you must surely know which is which."

"an old abandoned building;  an old friend"

"The extinguishers in the hallway are checked regularly to ensure they work in case of a fire. "

"The air we breathe is made of tiny atoms like oxygen and nitrogen. "