She opened it. The introduction said: “A collocation is a pair or group of words that are often used together. For example, we say ‘heavy rain,’ not ‘strong rain.’”

Emma smiled and pulled the blue book from her bag. “I learned that words have friends,” she said. “You have to use them together.”

“I did a mistake,” she told her teacher.

She discovered we catch a bus, catch a cold, and catch a ball. We save time, save money, and save someone’s life. We take a photo, take a break, and take an exam.

One rainy Saturday, she walked into a small second-hand bookshop. On a dusty shelf, she found a blue book with a promising title: English Collocations in Use (Elementary) .

Emma was a dedicated English student. She knew thousands of individual words: make , do , strong , heavy , tell , say . But when she tried to speak, her sentences sounded strange.