I never know how colorful my life would be until I ____ my first college teacher last term.

Each button, when ____, provides a piece of beautiful music.

In fact, I think it's very much nicer without the naughty boy, if you don't mind me ___ so.

_____ in 2011, the Beijing-Shanghai high-speed railway has benefited Qufu a lot.

_____ at the back of the temple is the Tianning Tower, which, _____154 metres into the sky, is the tallest tower of the kind in China.