总体翻译不错，个别稍作修改，供参考。

1. There is no one in the hall. The meeting must have been delayed.

2. That modern building looks much like a flying saucer. 用looks like。

3. Sichuan dialect is much the same as Hubei dialect. Sometimes, it is difficult for northerners to distinguish one from the other.

4. The very sight of the monument reminds me of the good friends who died in the battle. 好友用复数较好

5. He is lost in thought, oblivious of what his companions are talking about. （fellow通常只指男性）

6. What he did has nothing to do with her.

7. She couldn’t fall asleep, because her mind was preoccupied by her daughter’s illness. 原句从句没有谓语动词。

8. This matter has been on my mind for a long time.

9. He enjoys these parties and likes to rub shoulders with young people to exchange opinions on all kinds of issues. 二个谓语并列不用逗号。

10. It took several minutes for the meaning of his words to sink in. 本句强调大家理解他的意思花了较长的时间，故用it take time to do something结构。

11. The soil smells of fresh grasses. 土壤在此是特指的。

12. Could you spare me a few minutes? 突出不占用很长时间，用a few表示少。

13. Could you spare me one ticket?

14. The elderly man with gray hairs is a coppersmith by trade. 不定冠词还是要用的。