第12句：Of course,the conditions of work are very different:The Ponlytechnic is offering two-year contract which could be renewed,but the language school is only offering a year's contract,and that's a different minus.

六级词汇讲解:
该句较长，出现在长对话之中。of course放在句首或句末时起强调作用。offer意为“提供”，通常指主动提供。which引导的是two-year contract的定语从句，其中renew意为“使继续有效;延长期限”。minus此处意为“缺点”，是该句的听音难点所在。

六级考点归纳：
minus作名词时，有以下含义:
1.“负号，减号”。如:
Don't forget the minus when you add them up，
求和时别忘了负号。
2. “不利条件，不足，缺点”。如:
We should consider the pluses and minuses of the system.
我们应该考虑一下该系统的优点和缺点。