求圆心在直线x-3y=0上，且与y轴相切，在x轴上截得的弦长为42的圆的方程．

下列表述正确的是（  ）

A．¹⁶O与¹⁸O互为同位素；H₂¹⁶O与H₂¹⁸O互为同素异形体

B．Cl^－的结构示意图：

C．次氯酸分子的电子式为  

D．¹²C、¹³C、¹⁴C三种原子是碳元素的三种核素

准备在甲、乙两地间竖电杆，当两杆间隔为30米比间隔40米时多用电杆30根。求甲、乙两地相距多少米( )

A．2400

B．3600

C．1800

D．4600

In Europe, many people make friends between their countries through town twinning. Town or city twinning means two towns in different countries agree and decide to become “twins” with a sister-city relationship.

The people find pen friends in the twin town. They exchange newspapers and stamps. The school teachers discuss teaching methods with the teachers in the twin town. Officials visit the twin town for celebrations. Ordinary people travel to the twin town, too, but not very often if it is far away.

Sometimes, schools even exchange their classes for two or three weeks! For example, German middle school students study for a while at the school in their twin town in Britain, staying with British families. A few months later, their British friends come to study in Germany.

Many British towns are so pleased with the results of the twinning that they set out to find more than one twin town!

Tonbridge, a small town in Kent, for example, has twin towns in both Germany and France. Richmond near London has relationships with Germany, France and even a town in a Balkan(巴尔干半岛的) country!

Town twinning can help make friends. It helps students improve their language skill, and also helps people to understand the differences between nations.

小题1:Which is the best title for the passage?

A．Town Twinning

B．Friendly Towns

C．Exchanging Teachers and Students

D．Peace and Understanding小题2:Which of the following is NOT mentioned in the passage?

A．Twin towns exchange newspapers and stamps.

B．Twin towns exchange business skill.

C．Schools in twin towns exchange classes for a period of time.

D．Ordinary people travel to the twin town.小题3:Twin towns develop ____________.

A．between European countries and China

B．in the English-speaking countries only

C．in the same country

D．between different countries小题4:How many countries are mentioned in this passage?

A．7

B．6.

C．5

D．4小题5:One of the advantages of town twinning is to ________.

A．earn more money

B．set up schools

C．improve students’ language skills

D．develop industry and agriculture

职工因工致残被鉴定为一至四级的，应当退出生产、工作岗位，终止劳动关系，发给工伤伤残抚恤证件。

案情：甲乙共有店面一间，各有一半份额，产权证登记在甲一人名下。乙不在家，甲与丙签订书面租赁合同，租期4年，未办理租赁登记。当年，在丙租赁期间中，甲未通知乙、丙就将该店面房出售给丁，并在该年的8月1日办理了所有权转移登记。某日，戊酒后驾车失控冲撞该店面，致丙自行未悬挂妥当的招牌掉落而砸中一路人庚，庚花去医药费1万元，由丙支付。
问题：

8月1日之后，该租赁合同应该如何履行