No.PZ2018062002000035 (选择题)这道题是哪章节课程讲到的知识？

NO.PZ2018062002000035 问题如下 The following limit orr stanng in the stock’s orr book:Suppose Carl submittea y orr with a limit priof $ 20.87 ansol1,000 shares, anno more investor submits a buy orr after he submittethe orr. Whis the average prifor Carl’s transaction？ A.$21.70. B.$21.28. C.$21.05. Carl’s average tra priis:21.28=300×21.89+400×21.02+200×20.88300+400+20021.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}21.28=300+400+200300×21.89+400×21.02+200×20.88​Carl's orr will fillewith the most aggressively pricebuy orr firstly, whiis Fiona’s orr for 300 shares $21.89. Carl still remaining 700 shares not sell. Philip’s orr for 400 shares $21.02 is the seconaggressively pricebuy orr, after the orr wfilleCarl still have 300 shares to sell. bbie’s orr for 200 shares $20.88 is the thiraggressively pricebuy orr, he still h100 shares to sell after the thirorr takes place. Liam’s orr for 1,000 shares $20.70 is the next buy orr, but the priof this orr is lower thCarl's requirelimit price, therefore, no more transactions ccarrieout.考点Instructions Of Transaction Processes这道题表格中给了市场上买方和卖方愿意出的价格和需求量，问如果C同学想要以不低于20.87的价格卖出1000股，那么它的平均成交价格是多少。这道题是从卖股票的角度考虑，那么你就要看看当前市场上有多少人想买，只有买价大于20.87的部分才能成交，从表格可以看出只有bbie\Philips\Fiona出的买价高于20.87，因此C同学只能卖出900股。那么总共卖出的交易价格就等于\(21.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}\) 如果买方仍然是300share@21.89, 400share@21.02，现在investor下了一个500share@20.87的all or nothing buy orr。那么订单会在21.89执行300+在21.02执行200；还是会因为在21.89的买单不够500share，而导致无效无法成交？

NO.PZ2018062002000035 问题如下 The following limit orr stanng in the stock’s orr book:Suppose Carl submittea y orr with a limit priof $ 20.87 ansol1,000 shares, anno more investor submits a buy orr after he submittethe orr. Whis the average prifor Carl’s transaction？ A.$21.70. B.$21.28. C.$21.05. Carl’s average tra priis:21.28=300×21.89+400×21.02+200×20.88300+400+20021.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}21.28=300+400+200300×21.89+400×21.02+200×20.88​Carl's orr will fillewith the most aggressively pricebuy orr firstly, whiis Fiona’s orr for 300 shares $21.89. Carl still remaining 700 shares not sell. Philip’s orr for 400 shares $21.02 is the seconaggressively pricebuy orr, after the orr wfilleCarl still have 300 shares to sell. bbie’s orr for 200 shares $20.88 is the thiraggressively pricebuy orr, he still h100 shares to sell after the thirorr takes place. Liam’s orr for 1,000 shares $20.70 is the next buy orr, but the priof this orr is lower thCarl's requirelimit price, therefore, no more transactions ccarrieout.考点Instructions Of Transaction Processes这道题表格中给了市场上买方和卖方愿意出的价格和需求量，问如果C同学想要以不低于20.87的价格卖出1000股，那么它的平均成交价格是多少。这道题是从卖股票的角度考虑，那么你就要看看当前市场上有多少人想买，只有买价大于20.87的部分才能成交，从表格可以看出只有bbie\Philips\Fiona出的买价高于20.87，因此C同学只能卖出900股。那么总共卖出的交易价格就等于\(21.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}\) 这里面说c同学是想卖，那别人就是想买。为什么不是用ask价啊？不是aler想卖吗？

NO.PZ2018062002000035 问题如下 The following limit orr stanng in the stock’s orr book:Suppose Carl submittea y orr with a limit priof $ 20.87 ansol1,000 shares, anno more investor submits a buy orr after he submittethe orr. Whis the average prifor Carl’s transaction？ A.$21.70. B.$21.28. C.$21.05. Carl’s average tra priis:21.28=300×21.89+400×21.02+200×20.88300+400+20021.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}21.28=300+400+200300×21.89+400×21.02+200×20.88​Carl's orr will fillewith the most aggressively pricebuy orr firstly, whiis Fiona’s orr for 300 shares $21.89. Carl still remaining 700 shares not sell. Philip’s orr for 400 shares $21.02 is the seconaggressively pricebuy orr, after the orr wfilleCarl still have 300 shares to sell. bbie’s orr for 200 shares $20.88 is the thiraggressively pricebuy orr, he still h100 shares to sell after the thirorr takes place. Liam’s orr for 1,000 shares $20.70 is the next buy orr, but the priof this orr is lower thCarl's requirelimit price, therefore, no more transactions ccarrieout.考点Instructions Of Transaction Processes这道题表格中给了市场上买方和卖方愿意出的价格和需求量，问如果C同学想要以不低于20.87的价格卖出1000股，那么它的平均成交价格是多少。这道题是从卖股票的角度考虑，那么你就要看看当前市场上有多少人想买，只有买价大于20.87的部分才能成交，从表格可以看出只有bbie\Philips\Fiona出的买价高于20.87，因此C同学只能卖出900股。那么总共卖出的交易价格就等于\(21.28=\frac{300\times21.89+400\times21.02+200\times20.88}{300+400+200}\) 都还没讲的知识点发出来让我做什么？

NO.PZ2018062002000035 老师上课举例说如果买方定了150块钱买，现在市场价10块，那成交价还是10块，不是150，这是为了防止市场波动，我还清楚记得这个例子和例子的数据。请问怎么理解老师讲的例子和这道题？不是矛盾吗？谢谢