A landing on Mars is within the _____ of current physical theory.

He had been practicing his spoken English with the ____ of working as a volunteer for World Expo Shanghai and his dream finally came true.

Some of the passengers told the reporters about their_____in the burning train.

Mo Yan's winning of 2012 Nobel Prize in Literature shows the world's ________ of China's contemporary literature.

There is no doubt that all this puts a large _________ on a teacher with a large number of classes.