24. With online course Crazy English has over 20 million students all over China _____the class through the Internet.
More and more people choose to shop in a supermarket as it offers a great _____ of goods.
Mr. Wang has been selected_________ chairman of the conference.
Paper-making began in China and from here it ________ to North Africa and Europe.
He wrote this article ____this great communist fighter, Dr. Bethune.
As a result of the heavy fog, the highway has been closed up until further _______ .