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你要通过平面镜看到自己的全身，平面镜的高度至少是你身高的一半．请问，你能通过墙上固定的一小片平面镜观看墙前整个运动场吗？请作图说说你的理由．

答案

答：如图所示，A、C、B分别表示人的头顶、眼睛和脚的位置．EF为平面镜位置，

，

由平面镜成像特点可确定A′C′B′为ACB的像，因为OC=OC′，所以OC=

1
2
CC′，

EO=

1
2
A′C′，FO=
1
2
B′C′，EF=
1
2
A′B′=
1
2
AB

EF为平面镜的最小长度，AB为人的身高，故镜子至少为人身高的一半．

能通过墙上固定的一小片平面镜观看墙前整个运动场，可以通过眼睛的移动进行观察．

完形填空

任务型阅读 (共30分，每题2分)

　　Passage E

Sending E-cards on the Internet

　　The Internet has changed our habits, including our habit of sending greeting cards. There are many e-card websites that make it so easy to find the right greeting cards. They have greatly changed the way we send greetings to each other.

　　Our lives have become so busy that we have limited personal time . These e-card websites have allowed everyone to easily share their feelings and emotions(感情) with the people they love. They contain (包括)plenty of greeting cards that can be used immediately. The users can choose any card they like, from festival greetings to birthday wishes. In fact, e-cards are perfect for any event. That’s why more and more people like to send e-cards. If the users are interested in making their own greeting cards on the Internet, they can create a card within only a few minutes.

　　Another benefit(好处) of e-card websites is that they have made it possible for us to send top quality cards to our beloved(心爱的) ones and surprise them with cheerful greetings. They allow us to send our greetings on a specific(特定的) date. So we can plan for the occasion(场合) when we want to send the card. For example, we can send our e-card on a certain day and then visit the person with some flowers the next day. This will surely create a good impression(印象) on the person we love.

　　We have never forgotten the importance of saying sorry to our beloved ones. But sometimes we fail to do so because, we are not brave enough to face those we hurt. Some e-cards on these websites allow us to express our feelings in a more thoughtful way.

　　Although some people still would rather buy traditional cards in the shops for the persons they love, especially when they want the cards to last a long time, more and more people are choosing to send greetings on the Internet.

　　
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单项选择题 共用题干题

关于卵巢生殖细胞肿瘤。

关于卵黄囊瘤，叙述错误的是（）。

A.微囊或网状是卵黄囊瘤最常见的结构

B.透明小体和基底膜样物质PAS染色（+）

C.很少发生于40岁以上

D.Call-Exner小体是其特征

E.是向胚外组织分化的生殖细胞肿瘤
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