不属于恒牙正常萌出顺序的是（） A.上颌：6124537 B.上颌：6123457

一个数的平方是4，这个数的立方是（　　）

A．8

B．-8

C．8或-8

D．4或-4

若2x-1=3，3y+2=8，则2x+3y=（    ）。

1930年，（）写成《中国古代社会研究》。

常用设备及管道防腐蚀施工要求是( )。

A．设备、管子、管件外壁附件的焊接，必须进行中间检查

B．转动设备在防腐蚀施工前，应具有静平衡或动平衡的试验报告

C．设备、管子、管件的加工制作，必须按设计文件规定进行

D．受压的设备、管子、管件在防腐蚀施工后，必须按有关规定进行强度或气密性检查

E．地施工配合比有要求的防腐蚀材料，其配合比应经试验确定，并不得任意改变

The development of e-commerce may well bring the world into a brand new era of "electronic currency". At the moment, (51) areas in Europe, the United States and Asia have already started studying the possibility of an electronic currency. Electronic currency is not only about currency. It (52) to an entire finance system on the Net. It includes a virtual numeric currency, an electronic system of withdrawals, transfers and loans, and (53) cards of all shapes and sizes. The (54) of an electronic currency system implies the emergence of "virtual banks" and "virtual enterprises". Actually, the first virtual bank appeared in the US in 1995. (55) it is a small and insignificant bank, it represents the trend of the future. In time to come, we may even have to (56) the familiar paper currency.

As the Net pushes the economy (57) rapidly, the economy is also bringing the Net market forward, resulting in the Internet itself becoming the world’s largest emerging market. Of course, this is just the beginning. Although there are many companies which made huge profits (58) in the Internet market, they tend to be small companies. To date, most companies are making losses. The competition in the knowledge-based economy will also be more (59) This will definitely promote (60) and more efficient cooperation.

58().

A.invested 

B.comparing 

C.investing 

D.compared