Examples:

• Yesterday, I was in the library studying for my exams.
• When I heard the news, I was in the library reading a book.
• As I was in the library, I ran into an old friend I hadn't seen in years.
• During lunch break, I was in the library catching up on some reading.
• Last weekend, I was in the library researching for my history paper.
• While I was in the library, I noticed how peaceful and quiet it was compared to outside.
• Before the lecture, I was in the library reviewing my notes from the previous class.
• As soon as the library opened, I was in the library eager to find a new novel to read.
• Despite the rain, I was in the library studying, determined to stay focused.
• While everyone else was out partying, I was in the library working on my project.