I don’t smoke now, but I _______ for more than twenty years.
--- Did you go for the Shanghai Expo? ---- I _____ to, but I decided to stay with my sick mother at the last minute.
With so much noise of the traffic, I couldn’t ____ and do my research work.
Zhang Yinying has trained continuously for six hours. ______ that she is tired out.
I wonder ______ that my children have picked up such words.
Now then, children, it’s right time you ______.