38. She saw that he was so angry. She left the classroom. A. She didn't want to make him angry, so she left the classroom. B. She left the classroom when she saw he was so angry. C He was very angry when he saw her leaving the classroom. D. Having been seen to be angry, she left the classroom. 39. How old do you think this beautiful city is? A. When did you build this beautiful city? B. How many beautiful cities did you built? C. When was this beautiful city built? D. How old were you when you built this city? 40.The thick fog made it impossible for the plane to land. A. The plane could land as the fog was hardly thick. B. The plane cannot land because the fog is thick. C. It was possible for the plane to land although the fog was thick. D. The plane was unable to land because of the thick fog.