在订单匹配原则方面，我国采用（）A．价格优先原则 B．时间优先原则 C．客户优先原则

写出⑴⑵化学符号的含义，并按要求完成⑶⑷。

⑴ 2N________；

⑵ CO₃^2－_________；

⑶ 的离子符号__________；

⑷ 中“+2”的含义__________。

疫苗可产生哪一类免疫（）

A.自然自动免疫

B.自然被动免疫

C.人工自动免疫

D.人工被动免疫

E.非特异性抵抗力

（）是指保险人已放弃某种权利的，日后不得再向被保险人主张。

A.确认保证

B.承诺保证

C.弃权

D.禁止反言

Bolivia has a population of three and a half million. About one tenth of the total population are white; one-fourth are mixed Indians and white; and more than half are full-blooded Indians. The government and the industries are under the control of the white people.

The Indians today live in much the same way as their ancestors. Most of them are farmers. Many work in the mines, for mining is the most important industry on Bolivia’s. Of all the mining products, tin is the most important, which makes up three-fourths of all Bolivia’s exports. The eastern slopes of the Andes, since there are very few roads there, are fertile but not highly developed. The two primary means of transportation are river boats and porters. East of the hill region is the great plains where tropical plants are grown. A serious problem for Bolivia is the transport of food from the warm regions, where it is grown to the mountainous regions, where most of the people live.

Bolivia gained its independence from Spain about a hundred years ago. It has been slow in developing, but its rich resources promise a better future in it.

小题1:.

The majority of the Bolivian population are        .

A．full-blooded Indians

B．mixed Indian and white

C．white citizens

D．all whites and mixed-blooded people小题2:.

. The Indian’s way of life today is       .

A．quite different from that of their ancestors

B．quite interesting

C．almost the same as their ancestors’

D．very exciting小题3:.

The main product Bolivia exports is        .

A．tropical plants

B．gold and silver

C．tin

D．food小题4:.

Bolivia has been slow in developing, but it has hope for a better future because of its        .

A．mining products

B．rich resources

C．independence from Spain

D．two primary means of transportation

通常显黄色至橙色的是( )

A．查耳酮
B．黄酮和黄酮醇
C．花色素
D．二氢黄酮
E．二氢黄酮和异黄酮