9. Several important legal questions arose in the contract negotiations.
在合同谈判中出现了一些重要的法律问题。
还能这样说：
There exist some critical legal questions in the contract negotiations.
Some significant legal questions emerge from the contract negotiations.
应用解析：
legal affairs 法律事务；
legal adviser 法律顾问；
take a legal action 提起诉讼

10. The talks were hung up for a week.
谈判中止了一个星期。
还能这样说：
The talks had terminated for a week.
The talks had suspended for seven days.
应用解析：
Hang it (all) ! 见鬼！该死！岂有此理！（表示反对、不耐烦、惊异等）；
hang it out 拖延，故意拖拉

11. We are responsible to replace the defective ones.
我们保换质量不合格的产品。
还能这样说：
We promise to change the inferior goods.
We guarantee that the poor-quality commodity can be changed.
应用解析：
replace指代替某人或取代已经失去的、毁坏的或用坏的东西；
supersede系正式用语，指用更好的、最新的东西替换过时的或无用的东西；
supplant指以武力、欺骗等手段替代原来的人或其职位。

12. The negotiations broke down because neither side would compromise.
由于双方都不愿让步，所以谈判破裂了。
还能这样说：
As neither side would give in, the talks broke down.
Since both sides didn't want to make a concession, the negotiations came to nothing.
谚语：
There is much to be said on both sides.
公说公有理，婆说婆有理。