老师您好，可以解释一下第16题吗

请问，cost of goods sold 和cost of sales有什么区别？为什么减值了，cost of sales is higher

老师你好，这个指令同时也是market order呀？应该是同时是执行指令和有效性指令吧？

这里x拔的期望，为什么等于x拔的均值呢？期望不是加权平均的意思吗，这里为什么又可以只看成均值而不需要加权呢？

老师你好，Robert’s exposure to the risk of the stock of the Michelin Group is: 这句话中文翻译是啥意思？The exposure as a result of the long call position is long. The exposure as a result of the short put position is also long。这里的exposure 是什么意思？

为什么价格下降，demand加大curve右移不应该价格上升嘛

这里是不是写错了，样本均值的方差是Sx拔才对吧

An investor buys a 10-year bond with a 7% annual coupon and a YTM of 6.5%. The YTM for the bond increases to 7.5%, just before the first coupon payment is made. Assuming coupon payments are reinvested at the YTM, the investor's return when the bond is held to maturity is: 这道题我算了一下数字，答案是否是6.63%？

老师，请问一下，最后一排，non-price competition is absent 是什么意思呀？

write a put 是卖出看跌期权吗？为什么不写成sell a put ？那 write a call 又是啥？