为了估计某水池中鱼的尾数，先从水池中捕出2000尾鱼，并给每尾鱼做上标记（不影响存活），然后放回水池，经过适当的时间，再从水池中捕出500尾鱼，其中有标记的鱼为40尾，根据上述数据估计该水池中鱼的尾数为（    ）

A．10000

B．20000

C．25000

D．30000

根据短文内容，在空格中填入一个合适的单词，单词的首字母已给出。

Some humor can be cruel but some people seem to enjoy seeing other people’s bad luck at times. Perhaps it makes us feel more c 小题1:   with our life because we feel there is someone else w  小题2:    off than ourselves. However, Chaplin made people laugh at a time when they felt depressed. The character in The Little Tramp was a social f  小题3:  , but he won the love of audience for his determination to o 小题4:     difficulties and being kind to others. In his film The Gold Rush, Chaplin successfully made a sad situation e  小题5:   by eating a boiled shoe.