商品房预售合同的效力。

治血热便血，在下列药物组中首选（）

A.地榆、藕节

B.地骨皮、菊花

C.熟地、地榆

D.地榆、槐花

E.槐花、红花

阅读理解。

     Many large cities in the United States have an area called Chinatown. Each of them was set up by people

who came from China. For example, Chinatown in San Francisco, California, began in the 1840s. The Chinese

immigrants (移民) came to America to look for gold. Then the area they lived in later became known as

Chinatown.

     Chinatowns were also setup in cities in the western states of Oregon and Washington during the middle of

the 19th century. Many Chinese immigrants in these areas helped build the first railroad system across the

United States. However, after the work ended in 1869, many Chinese moved to the eastern and middle parts of

the United States.

     Chinatowns can also be found in cities outside the United States. For example, the first Chinese immigrants

in London arrived in the late 18th century. They were men who worked for the East India Company. Later, the

Chinese immigrants opened small stores and restaurants there.

     Today, many people visit Chinatowns. They have special Chinese gates and walking areas for visitors.

Chinatowns around the world are not only places where Chinese people live and work. They are also places

where visitors can learn more about Chinese culture and traditions.

1. In the 1840s, a large number of Chinese people went to America to _____.

A. look for jobs

B. look for gold

C. build Chinatowns

D. build the railway

2. According to the passage, Chinatown in Oregon was set up about _____ years ago.

A. 100

B. 160

C. 200

D. 300

3. According to the passage, Chinatown can also be found in _____ outside the United States.

A. London

B. Oregon

C. Washington

D. San Francisco

4. Visitors come to Chinatowns because they want to _____.

A. taste the food there

B. do shopping there

C. make some Chinese friends

D. learn more about Chinese culture

5. What's the best title of the passage?

A. The History of Chinatowns

B. The Visitors to Chinatowns

C. The Culture about Chinatowns

D. The Immigrants in Chinatowns

在配置钢筋网的水平灰缝中，应先铺一半厚的砂浆层，待放入钢筋网后再铺一半厚砂浆层，使钢筋网居于砂浆层厚度中间。( )

我们常见的空中飞行的动物是（）

A.都是脊椎动物

B.都是无脊椎动物

C.既有脊椎动物又有无脊椎动物

D.既不是脊椎动物，也不是无脊椎动物

160km/h≥＞Vmax＞120km/h正线道岔。水平作业验收管理值为（）。

A、3mm

B、4mm

C、6mm

D、5mm