sum的值为0，则result=sum==01:num/sum的值为______。

DNA连接酶催化的化学反应能够

A．填补引物遗留下的空隙
B．水解引物
C．向3′-OH末端加入dNTP
D．生成磷酸二酯键
E．生成氢键

The film is well worth _____, so I suggest you go and see it. [ ]

A. to be seen

B. seeing

C. of being seen

D. being seen

某结构用钢筋混凝土梁，混凝土的设计强度等级为C30，施工釆用机械搅拌、机械振捣，坍落度为30～50㎜，根据施工单位近期同一品种混凝土资料，强度标准差为3.2MPa。试回答以下问题（多选题）：

确定配制强度时，以下说法正确的是

A.该梁混凝土配制强度为35.26Mp

B.若无历史统计资料，该梁混凝土配制强度为38.22Mp

C.若无历史统计资料，该梁混凝土配制强度为36.58Mp

D.若现混凝土的设计强度等级为C40又无历史统计资料时，该梁混凝土配制强度为49.87Mp

E.若现混凝土的设计强度等级为C40，根据施工单位近期同一品种混凝土资料，强度标准差为3.2Mpa时，该梁混凝土配制强度为45.26Mp

Going home for Christmas is a tradition of the holiday season. No matter where you may be the rest of the years, being at “home” with your family and friends for Christmas is a “must”. The Thanksgiving and Christmas holidays are the busiest times of the year at airports, train stations and bus stations. It seems that all America is on the move and Americans are on their way to spend the holidays with their loved ones.

This means that the house will be full of cousins, aunts and uncles that might not see each other during the year. Everyone joins in to help in the preparation of the festival. Some family members get to choose a Christmas tree to buy and bring home. Others decorate the house or wrap presents. And of course, each household needs to make lots of food!

At Christmas Eve gatherings adults have eggnog, which is made of cream, milk, sugar, eggs and brandy. Plenty of  eggnog  or hot cocoa is on hand in colder climates for carolers, or people who go from house to house sing Christmas carols to their neighbors.

Long ago, each child hung a stocking, or sock, over the fireplace. Santa entered down the chimney and left candy and presents inside the socks for the children. Today the tradition is carried on, but the socks are now large red sock-shaped fabric bags still called stockings. Each child can’t wait to open his or her eyes to see what Santa has left in the stocking.

Giving gifts is a Christmas tradition. However, in recent years, more and more people have complained that Christmas is too commercialized(商业化) especially in large cities. Store owners begin advertising and decorating very early in hopes of selling more goods. Some people believe that the origin of Christmas has been lost.

46．It is a traditional custom for Americans ____________.

A．to buy Christmas trees and bring them to churches for Christmas

B．to drink beer on Christmas Eve

C．to go home for Christmas with their family and relatives

D．to hung stockings on the chimney

47．The underlined word “eggnog” in the third paragraph is a kind ____________.

A．drink                  B．food                   C．egg                     D．present

48．Each child hung a stocking over the fireplace in order to____________.

A．get some eggnog                                  B．have a look at Santa

C．get some candy and presents                 D．get some money from his/ her parents

49．The last paragraph wants to tell us that  ____________.

A．giving gifts is a Christmas tradition     B．giving gifts is getting more and more commercialized

C．store owners hope to get more presents  D．people think there will be no Christmas in the future

下列关于对象的串行化的说法中，错误的是( )。

A．对象串行化定制分为两个层次：部分串行化和完全串行化

B．对象永久化是将对象存在内存中

C．对象串行化是对Java对象的读、写的过程

D．对象串行化必须实现Serializable接口