题目内容：

On a foggy day, Polly left work at four o’clock. Once out in the street, she walked quickly towards her usual bus stop. 1..雾太浓了公交车跑不了那么远, so she had to take the Underground back home.

As Polly observed the passengers on the train, she had a feeling that 2.. she was being watched by a tall man in a dark overcoat. But soon the man was nowhere to be seen. Finally the train arrived and Polly got out of the station. Outside, the fog lay like a thick, grey cloud. There was no one in sight. As she walked along the narrow street, she heard the sound of footsteps approaching. Polly could feel her heart beating with fear. She wanted to run, 3.. but fear held her still. Then a man’s voice came out of the darkness. “Is anybody there?” Polly hesitated, and then answered, “Hello, I think I am lost. ” A few seconds later, a hand reached out and grasped her arm. 4..波莉发现自己正向上盯着一位老人的脸看. It was the old blind man who sent Polly back home safely.

When Polly arrived home, 5.. she thanked the old man for coming to her aid and invited him to go in to rest for a while. But the old blind man refused. He said a fog that bad was rare and he thought it gave him a chance to pay back the help that people gave him when it’s sunny.