问题 问答题 简答题

什么是双鉴探测器?市面上常见的双鉴探测器有哪些?

答案

参考答案:

为了克服单一技术探测器的缺陷,通常将2种不同技术原理的探测器整合在一起,只有当2种探测技术的传感器都探测到人体移动时才报警的探测器称为双鉴探测器。市面上常见的双鉴探测器以微波+被动红外居多,另外还有红外+空气压力探测器和音频+空气压力的探测器等产品。

单项选择题 A1/A2型题
阅读理解

阅读理解。

    People in the United States honor their parents with two special days: Mother's Day, on the second Sunday

in May, and Father's Day, on the third Sunday in June. These days are set aside to show love and respect for

parents. They raise their children and educate them to be responsible citizens. They give love and care. These

two days make us think about the changing roles of mothers and fathers. More mothers now work outside the

home. More fathers must help with child care. 

    These two special days are celebrated in many different ways. On Mother's Day people wear carnations

which have two colors. A red one symbolizes (象征) a living mother. A white one shows that the mother is

dead. Many people attend religious services to honor parents. It is also a day when people whose parents are

dead visit the cemetery. On these two days families get together to have parties at home, as well as in

restaurants. These are days of fun and good feelings and memories.

    Another tradition is to give cards and gifts. Children make them in school. Many people make their own

presents. These are valued (珍爱) more than the ones bought in stores. It is not the value of the gift that is

important, but it is "the thought that counts". Greeting card stores, florists, candy makers, bakeries, telephone

companies, and other stores do a lot of business during these holidays.

1. Which of the following is NOT a reason for children to show love and respect for parents?

A. Parents bring children

B. Parents give love and care to children

C. Parents educate children to be good persons.

D. Parents pass away before children grow up

2. Which do you think is right about "carnation"?

A. It has only two kinds of colors.

B. It refers to the special clothes people wear on Mother's Day or Father's Day.

C. It's a kind of flower showing love and best wishes.

D. People can wear carnations only on the second Sunday in May.

3. What do you know from the passage?

A. Mother's Day and Father's Day are both in May.

B. Fewer women worked outside the home in the past

C. Not all the children respect their parents

D. Fathers are not as important as mothers at home

4. On Mother's Day and Father's Day, _____.

A. people usually have family parties

B. everyone goes to visit the cemetery

C. children always go to parents' home

D. hand-made cards are the most valuable gifts