某生活小区鲜奶店每天以每瓶3元的价格从奶场购进优质鲜奶，然后以每瓶6元的价格出售，如果当天卖不完，剩余的只有倒掉．店主记录了30天的日需求量（单位：瓶），整理得下表：

（1）求这30天内日需求量的众数；

（2）假设鲜奶店在这30天内每天购进28瓶，求这30天的日利润（单位：元）的平均数；

（3）以30记录的各需求量的频率作为各需求是发生的概率．若鲜奶店每天购进28瓶，求在这记录的30天内日利润不低于81元的概率．

    The clock struck（敲）eight，but I was still on the bed．I could hear it was blowing strongly．“It must be windy outside，” I thought． I came to the small town a week ago． I sold some clothes to a ten and friends．So I tried to meet the manager and ask him to pay for them．I was out of luck（运气不好）．He went to London and I had to wait for him here．There was no theatre here but a cinema．The films were all too old．I preferred staying in the small hotel to sitting in the cold cinema． Half an hour later，I felt hungry．I had to get up．It was white everywhere and some children were skiing down the hill．On my way to the small restaurant，I saw a boy fall on to a rock （岩石）．I ran to him quickly and carried him to a hospital．Soon his parents came here．Now I knew the boy was just the manager's son．He thanked me very much and gave me the money after we had a dinner．

下面对骨骼肌的叙述中，不正确的是（    ）