This problem is said _______ three times, but he still can’t understand it.
A. to have been explaining B. to have explained
C. having been explained D. to have been explained
---I heard that you made a bicycle trip to the 2010 World Expo of Shanghai alone.
---No. Actually, my friend Bob ________ me.
A. accompanied B. conducted
C. instructed D. received
I went the village yesterday_________ to see my uncle, who lived there for 20 years.
A. special B. especially C. specially D. especial
The problem of the present world is that those who are imaginative have little experience_________those who are experienced have weak imagination.
A．unless B．although C．because D．while
He ran all the way to the station only _______________ the train had already left.
A. find B. to find C. finding D. to have found
