III
9. It isn't easy to speak English 
10.you didn't remember to post the letter 
11.it takes six hours to fly from London to New York 

II
5. The poem which he read to us yesterday has been translated into several language  
6.if mr. Ba wasn't too old, he could continue the work
7.in spite of its appearance, the new restaurant doesn't appear to attract much business
8.he sea was rough enough for the children to swim in