As high school students, it’s very important to keep ourselves ______ of what’s happening home and abroad every day.

By the time you finish the book, you _______________ more about Chinese history.

This book is said to be a special one, which __________many events not found in other history books.

My mind wasn't on what he was saying so I'm afraid I ______ half of it. 

—How do you like the glasses? —This kind of glasses made by experienced workers________ comfortably.