I didn’t find out the answer_______ the end of the story.

Not only the young but also the old are getting interested _____ WeChat (微信).—They can communicate more freely.

The program Masters Lectures of CCTV is both interesting and instructive. No wonder it _______ a large audience.

With the change of the economic foundation the entire immense superstructure is _____ rapidly transformed.

Sam is doing some ______ about the ancient Silk Road.