tarnishing

"To get a good grade on the test, you need to answer the questions properly. "

"Washing light laundry with dark may cause your clothes to discolor."

"My friend told me there was something in the box, but I didn't know what it was yet. "

"My grandmother wore a beautiful pearl necklace to the family dinner. "

"The compromise on the school project was reached when each student agreed to contribute their strengths to the final presentation. "

"My grandmother's silverware set is beautiful; it's made of sterling silver. "

"The oxidation of iron causes rust to form on metal objects. "

"Careful storage of silver will prevent it from tarnishing."

"He polished up the chrome until it gleamed."

"The attraction of a good teacher to their students is often strong. "

"My sister's reputation for being organized helped her excel in school. "

"Bob says cats are friendlier than dogs, but I disagree."