镁铝合金的爆炸浓度下限是（）g/m3。 A．30  B．40  C．50  D．60

吴建民教授在《百家讲坛》节目中讲道：弱国当然是没有外交的……但是并不等于国家不是很强的时候，外交官就不能发挥作用。你看顾维均在1919年的时候，中国是弱国，五个代表，跑了四个，就他一个，没有任何指示，他拒签《凡尔赛条约》，我觉得中国人要很好地研究一下。吴教授要我们研究的是      

A．吸取弱国无外交的历史教训

B．强调当今社会发展经济，增强国力的重要性

C．顾维均强烈的爱国精神和高尚的民族气节

D．认识近代幻想依靠帝国主义来废除不平等条约，实现民族独立是不可能的

某学生测定一瓶失去标签的BaCl₂溶液的质量分数．他的实验步骤如下：

（1）从细口瓶中取出10g溶液于一个洁净的烧杯中，操作时，取下的瓶塞应 _________ 在桌面上，其理由是 _________ ；

（2）用胶头滴管向烧杯中滴加AgNO₃溶液直至不再产生沉淀为止．滴加试剂时，滴管要保持 _________ ，不要接触 _________ ，用毕，立即用蒸馏水洗干净；

（3）过滤时，要用一洁净的 _________ ，其下端轻轻靠在 _________ 的滤纸上，使混合物沿 _________ 流入过滤器；

（4）取沉淀物于蒸发皿中蒸干，并在充分干燥后进行称量，称得沉淀物2g，则计算该溶液的质量分数为 _________ ．

信息填空

     根据短文内容,从短文后的选项中选出能填入空白处的最佳选项.选项中有两项为多余选项.  

         1    You probably think you will never be a top student. This is not necessarily so, however.

Anyone can become a better student if he or she wants to. Here's how:

Plan your time carefully. When planning your work, you should make a list of things that you have to do.

After making this list, you should make a schedule of your time. First your time for eating, sleeping,

dressing, etc. Then decide a good, regular time for studying.     2   A weekly schedule may not solve all

your problems, but it will force you to realize what is happening to your time.

Find a good place to study. Look around the house for a good study area. Keep this space, which may

be a desk or simply a corner of your room, free of everything but study materials. No games, radios, or

television. When you sit down to study, concentrate on the subject.

Make good use of your time in class.     3    Listening carefully in class means less work later. Taking

notes will help you remember what the teacher says.

Study regularly. When you get home from school, go over your notes, review the important points that

your teacher is going to discuss the next day, read that material.    4  If you do these things regularly, the

material will become more meaningful, and you'll remember it longer.

Develop a good attitude towards tests. The purpose of a test is to show what you have learned about a

subject. They help you remember your new knowledge. The world won't end if you don't pass a test, so

don't be over worried. 

        5  You will probably discover them after you have tried these.

A. There are other methods that might help you with your studying.

B. Don't forget to set aside enough time for entertainment.

C. Take advantage of class time to listen to everything the teacher says.

D. No one can become a top student unless he or she works hard.

E. Maybe you are an average student.

F. Make full use of class time to take notes of what the teacher says in class.

G. This will help you understand the next class.

男性，18岁。因左侧脓胸行胸腔闭式引流术3个月，现已无引流液。查体：左胸廓塌陷，肋间隙变窄。X线胸片：肺内未见明显病变。

若考虑手术治疗，宜采取的术式是（）

A.胸腔闭式引流管持续冲洗

B.开放引流术

C.胸廓成形术

D.胸膜肺切除术

E.胸膜纤维板剥脱术

项目经理老姜不能确定在可交付成果的集成时可能遇到什么问题，但他决定不在当前时间段来考虑这个风险。该应对措施属于______。

A．风险转移
B．风险减轻
C．风险回避
D．风险接受