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问题 填空题

在四边形中,若有一组对角都为90°,另一组对角不相等的四边形我们称它为“垂直”四边形,那么下列说法正确的序号是       . (多填或错填得0分,少填酌情给分).

① “垂直”四边形对角互补;     ②“垂直”四边形对角线互相垂直;

③“垂直”四边形不可能成为梯形;④ 以“垂直”四边形的非直角顶点为端点的线段若平分这组对角,那么该“垂直”四边形有两组邻边相等.

答案

①③④

分析：根据四边形的内角和为360°，可得到①③正确；由于没有给定对角线的限制条件，不能得到②“垂直”四边形对角线互相垂直；利用三角形全等可以判断④正确．

解：根据四边形的内角和为360°，可得“垂直”四边形对角互补，所以①正确；

垂直”四边形对角线不一定互相垂直，②不正确；

因为“垂直”四边形有一组对角都为90°，另一组对角不相等的四边形，根据四边形的内角和为360°可得不能有相邻的角都为90°，则“垂直”四边形不可能成为梯形，所以③正确；

以“垂直”四边形的非直角顶点为端点的线段若平分这组对角，则可以得到被这条线段分成的两个三角形全等，则该“垂直”四边形有两组邻边相等，所以④正确．

故答案为①③④．

单项选择题

Questions 21～25


While other members of my team explored the wreck of a small Greek merchant ship that sank off the Turkish coast more than 2,400 years ago, I hovered above them in a submarine. One diver, an archaeologist, placed an amphora, or two-handled jar, inside a lifting basket. Another vacuumed sediment from the site by fanning sand into the mouth of a nearly vertical pipe. Two more were taking measurements, carefully, but of necessity quickly, for at this depth each diver had only 20 minutes to complete the morning’s assigned task. Any longer, and they would require lengthy medical treatment, to avoid the divers’ ailment known as the bends.
In four decades of diving on shipwrecks, I’ d been too engrossed in carrying out similar tasks to think of the families whose loved ones may have disappeared long ago. I had always concentrated on the technical features of my trade. I had stopped diving regularly 15 years before this exploration, turning over the bulk of the underwater work to a younger generation, but I continue to make inspection dives on most wrecks we excavate.
This was not just any wreck. Although I’ve been involved in uncovering the remains of much older ships, and of more than a hundred ancient shipwrecks along the Turkish coast. I had never even seen a wreck from the fifth century BC. Preliminary photographs of the cargo dated it to the third quarter of the century, during the Golden Age of classical Greece. Athens, then as now the major city in Greece, controlled an empire stretching from one side of the Aegean Sea to the other. None of this would have been possible without naval might and maritime commerce.
During our three-year exploration of the wreck we excavated examples of nearly every type of jar that the classical Greeks made for wine or water. Many types might have been used as tableware by the ship’s crew, but they were far in excess of what would have been required. We concluded therefore that they must have been cargo. We also discovered in the seabed two marble discs, which we guessed were the ship’s eyes. It has long been known from vase paintings that classical Greek ships—like those from other cultures—had eyes to give them life or help them see their way through the waves. Although warships were known to have had naturalistic marble eyes attached to them, most scholars assumed that the eyes on more modest merchant ships were depicted as simple circles painted onto the sides of the vessel.
Did the sailors who depended on these eyes for safety survive the ship’s last voyage They could have lived through the actual sinking. The ship was less than a hundred yards from land when it sank, so they might have swum towards the shore. And we know from Greek literature that some ships had lifeboats. But proximity to land and having lifeboats are no guarantee of safety. Even if some had swum to shore, it’s hard to imagine that many managed to crawl up on the exposed and sharp rocks while being smashed by waves like those that almost certainly sank their ship.

What does the writer suggest about himself in the second paragraph ______

A. He had developed every skill that was needed for exploring wrecks.
B. He had benefited by changing his role in explorations.
C. He was pleased he had started training younger divers.
D. He was aware he distanced himself from aspects of his work.
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判断题

对重要的进口商品和大型的成套设备，商检机构可以根据需要派出检验人员参加货物在出口国装运前的预检验、监造或监装。( )
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