患者男性，33岁，残冠，根尖病变。拔除过程中，远中颊根折断，取根时，牙根突然消失。捏

烤瓷熔附金属全冠在前牙切端至少应预备

A．2.5mm

B．1.0～1.5mm

C．2mm

D．3mm

E．0.5～1.0mm

根据山区、丘陵地区永久性水工建筑物洪水标准要求，对一级混凝土坝、浆砌石坝的水工建筑物来讲，在校核情况下的洪水重现期为( )。

A．10000～5000年

B．5000～2000年

C．5000～1000年

D．2000～1000年

单位建设面积为240㎡的健身房，可以不申请办理《施工许可证》。（　 ）

阅读理解。

        Microwaves may be great at warming up food, but what about warming people?    

        Using microwaves to directly heat owners of a room would save much of the energy wasted by

heating walls and furniture. And despite popular ideas about microwaves, this technique would be safe,

according to Charles R. Burlier of the Microwave Research Center in Marlborough, New Hampshire.

Low-power microwaves only penetrate (贯穿) the skin (low-power microwave penetration in a ham is

about 0.2 inches, for example) and with no negative effects.    

        To test this idea, Buffler subjected himself to microwaves in a special room using a standard

500-watt, 2459 MHz magnetron (磁控管). He found that a person will start to feel warmth at about 20

milliwatts per square centimeter (mw. / sq. cm. ) ; a satisfactory feeling of warmth occurs between 35 and

50mw. / sq. cm. By comparison, a person standing in noonday summer sun feels the amount of 85

mw. / sq. cm. And a frozen meat pie in your microwave oven receives about 1000 mw. / sq. cm.    

        In houses of the future, each room could be provided with its own magnetron, says Buffler. When

you stepped into the living room, for example, a motion detector (运动感应器)would turn on the

magnetron, filling the room with low-power microwaves. In the same way that a microwave oven heats up

a hamburger, but not the plate it’s on, you would feel warmth from the microwaves without changing the

temperature of your coffee table. (You could, however, make your favorite easy chair even more

comfortable by treating it with a radiation-absorbing chemical.)    

        While it might be some time before homeowners are comfortable enough with the idea to set up

whole-body microwave heaters in houses, Buffler says microwaves may attract livestock(家畜) farmers.

Lambs that are born outdoors in winter, for example, are frequently lost to cold. Microwaves could warm

the lambs safely and quickly.

1. Which of the following can tell the main idea of the passage?

A. A new heating system.

B. A new microwave oven.

C. A popular technique.

D. The magnetron.

2. According to Paragraph 2, which of the following does not describe the characteristics of a microwave

heater?

A. It directly heats people in a room.        

B. It heats walls and furniture in a room.

C. It is safe.                            

D. It saves energy．

3. The test conducted by Buffler shows that when a person feels comfortable warmth, he receives about

________________.

A. 20 mw. / sq. cm.

B. 40 mw. / sq. cm.

C. 60 mw. / sq. cm.

D. 85 mw. / sq. cm.

4. According to Paragraph 4, which of the following fills the room with low-power microwaves?

A. The magnetron.

B. The motion detector.

C. The microwave oven.

D. The radiation-absorbing chemical.

5. Which of the following statements about microwave heaters would Buffler most probably agree with?    

A. Microwave heaters will soon be widely used by homeowners.    

B. Microwave heaters sometimes make people feel uncomfortable.    

C. Perhaps microwave heaters will be first used by livestock farmers, who wish to protect their lambs in

winter.