问题如下：
Several different grades of corn can be delivered in a futures contract. Can the party with a long position who has entered into a particular contract specify which grade it wants?
选项：
解释：
No. Traders with short positions choose what will be delivered. When issuing a notice of intention, a trader with a short position specifies which grade will be delivered.
老师请解释一下讲义120页中 failure by the exchange to adequately distinguish grades of the underlying asset could cause the contract to fail? 与这道题中提的grades的意思
