英语it的用法练习（在线急求!）

英语it的用法练习（在线急求!）
Tell what the word“it”in each sentence refers to and what its function is.Then translate the sentences into Chinese.
1.It is very difficult to run a business successfully in this area.
2.There were some children crying in the burning house.It was terrible.
3.It is quite a long way from here to the island.
4.It was about four o'clock pm and not come.
5.It must be very interesting to know about the history of the islands.
6.I was told that it was dangerous to walk alone in the forest.
7.We couldn't get out of the building until in stopped raining.
原句子翻译！