— Why did you leave that position? — I      a better position at IBM. 

I_____in London for many years, but I’ve never regretted my final decision to move back to China.

Since the project has been ___ on well, you must ___ it on until it is completed.

. Since last year, the global economic slowdown ________ in many countries. It is expected that the world economy will not recover until the end of 2010.

By the time he realizes he _____ a mistake, it’ll be too late for him to change his mind.