问题
选择题
The cost of sales makes up a large part of the prices that _____.
A．are paid for all products
B．all products are paid
C．for which all products are paid
D．for all products paid
答案
答案：A
本题考查的是定语从句，that是引导定语从句的关系代词，指代the prices，在从句中充当被动语态的主语，故C是结构错，D是语态错，pay的搭配是pay the price for，因此for不可省，故B也错。