caffeine

"He drank the water I gave him."

"While walking to school, Sarah found a lost wallet on the ground. "

"Although he was unused to the situation, he tried to act naturally."

"He is a student of life."

"Coffee is a stimulant that helps many students stay awake during late-night study sessions. "

"The garden had a couple of trees, and a cluster of colourful plants around the border."

"The dancer's nervous muscles tensed before her performance. "

"My dad made a strong coffee before going to work. "

"The coffee bean contains caffeine, which is a stimulating alkaloid. "

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

"There are eight planets in the solar system."

"The central library is located in the heart of the city. "