16、Declining values for farm equipment and land,the collateral against which farmers borrow to get through the harvest season, are going to force many lenders to tighten or deny credit this spring. 这是正确的句子,关于怎么选出这个答案的没有疑问,但是:
请问:collateral明明是个可数名词,并且有复数形式,为什么这里不用collaterals呢? farm equipment and land 都是用来做抵押的啊