一个反射界面的终断点上,将产生左、右两支相位相关180°的绕射波.

下列关于我国疆域和行政区划的说法，正确的是：

A．位于东半球，亚洲东部，东临大西洋

B．领土最北端在漠河，最南在曾母暗沙

C．我国领土跨热带、北温带、北寒带

D．我国南部有北回归线穿过

下列方法与Applet显示无关的是( )。

A．paint

B．update

C．repaint()

D．draw

用括号内所给词的适当形式填空(每空不限一词)。

1. My hobby is reading comic books. What about ______ (you)?

2. Three ______ (five) of the students in our class are League members.

3. I don't think it's always right to be busy ______ (make) money all day.

4. He left home in a hurry because he had some problems ______ (solve) in his office.

5. I don't like traveling by plane. I think it's ______ (safe) to travel by train.

6.  ______ (luck), modern medicine can help people with eye problems in less developed countries.

7. They ______ (plan) a trip to Disneyland at this time yesterday.

8. —Excuse me, where is the ______ (lady) room. —It's over there.

9. I am ______ (excite) about passing the final exams.

10. He speaks Chinese very well though he is a ______ (Canada).

解决水资源地区分布不均衡的主要办法是（　　）

A．修建水库

B．建防洪大坝

C．植树造林

D．跨流域调水

The idea of test-tube babies may make you either delighted at the wonders of modern medicine or irritated while considering the moral, or legal, or technological implications of starting life in a laboratory. But if you’’ve ever been pregnant yourself, one thing is certain: You wonder what it’’s like to carry a test-tube baby. Are these pregnancies normal Are the babies normal The earliest answers come from Australia, where a group of medical experts at the Queen Victoria Medical Center in Melbourne have taken a look at the continent’’s first nine successful invitro pregnancies. The Australians report that the pregnancies themselves seemed to have proceeded according to plan, but at birth some unusual trends did show up. Seven of the nine babies turned out to be girls. Six of the nine were delivered by Caesarean section. And one baby, a twin, was born with a serious heart defect and a few days later developed life-threatening problems.What does it all mean Even the doctors don’’t know for sure, because the numbers are so small. The proportion of girls to boys is high, but until there are many more test-tube babies no one will know whether that’’s something that just happened to be like that or something special that happens when egg meets sperm in a test tube instead of a fallopian tube. The same thing is true of the single heart defect. It usually shows up in only 15 out of 60,000 births in that part of Australia, but the fact that it occurred in one out of nine test-tube babies does not necessarily mean that they are at special risk. One thing the doctors can explain is the high number of Caesareans. Most of the mothers were older, had long histories of fertility problems and in some cases had had surgery on the fallopian tubes, all of which made them likely candidates for Caesareans anyway.The Australian researchers report that they are quite encouraged. All the babies are now making normal progress, even the twin with the birth defects.

Which of the following statements about the experiment mentioned in the passage is true

A．Only the twins are defected.

B．Most of the babies are delivered by means of Caesarean.

C．There are some troubles during all mothers’ pregnancies.

D．One baby appears to be abnormal.