ack box is a necessary device on anairplane, which records its speed, direction and whether everything on theairplane______ normally

It was along the Mississippi River _________ Mark Twain spent much of his childhood.

China is famous for the Great Wall. Many people want to visit it.

Are you a teacher— No, but I ________ in Quanzhou No. 3 High School for 3 years.

The shy girl felt ______ and uncomfortable when she could not answer her teacher’s questions.