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Frogs and toads are usually poisonous.A．YB．NC．NG
Frogs and toads are usually poisonous.
A．Y
B．N
C．NG
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（请给出正确答案）
Frogs and toads are usually poisonous.
A．Y
B．N
C．NG
如果结果不匹配，请 联系老师 获取答案
更多“Frogs and toads are usually po…”相关的问题
Biologists are unable to explain why frogs are dying.
A．Y
B．N
C．NG
Frogs are important in the ecosystem because they control pests.
A．Y
B．N
C．NG
An acidic environment is favorable to .
A. frogs
B. bacteria
C. oxygen-consuming plants
D. algae and fungal growth
South America Located mostly(most) in the southern half of the earth, South America is a very（41）_____(interest) continent. The northern part of the continent is（42）_____(cover). By the Amazon Rainforest, which is home to thousands of the plant animal species. It is a very important force（43）_____(shape) the world's weather and climate patterns. And it is also important for the（44）_____(develop) of the economy of South America. Products such as chocolate, rubber, coffee and many kinds of medicine are（45）_____(harvest) from the plants found in the rainforest. Even the liquid from the skin of some species of tree frogs are being used as（46）_____(experiment) medicines. Other parts of South America are very（47）_____(differ).The Andes Mountains spread over the（48）_____(west) part of South America. The ranges, about 5500 miles long, are a continuous barrier, with many peaks rising beyond 2000（49）_____(foot). Southern South America is an extremely（50）_____(wind) and cold place where many species of penguins（企鹅）, seals and whales live. _____
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Shoichi knew that Japan had lost the war, but the humiliation of defeat kept him from surrendering. So he stayed in the jungle, living on what he could search out. He ate mostly insects, snails, frogs and rats.
In 1972, U.S. authorities finally convinced Shoichi to "surrender". He was sent back to his homeland. Shoichi's returning home attracted a lot of attention. When a department store in Tokyo exhibited his jungle clothes and tools, more than 350,000 curious people came to view them. After spending some time back in civilization, Shoichi met a forty-five years old widow. The old soldier and the widow fell in love and married. After their wedding, the couple took a honeymoon trip to the island of Guam.
(30)
A．The island of Guam.
B．The battles on Guam during World War II.
C．Yokoi Shoichi's marriage.
D．A Japanese soldier who hid on Guam.
听力原文： One of the greatest mysteries of nature is the instinct to migrate. Every year, millions of creatures feel the need to migrate and most people have seen the arrival or departure of migrating flocks of birds. In England, for example, we always know when Autumn is coming, because flocks of swallows sit on the telegraph wires. Migration is not only seen in birds but also in reptiles, for example, turtles, frogs and toads. Insects, such as locusts and butterflies; fish, such as eel, salmon and tunas and mammals, such as reindeer, seals, lemmings, whales and bats. Many of these creatures can find their way over long distances. And how they do it is a mystery and a wonder to everyone, especially for those of us who have difficulty even reading a map covering 100 miles. There are several suggestions about how they navigate. Firstly, it is suggested, they navigate by using stars and planets for guidance. Secondly, some people think that these migrating mammals find their way by following the pole of the earth's magnetic field. Thirdly some people think that migrating birds, insects and animals follow a certain smell or scent. Fourthly, another group of people believe that animals migrate by recognizing geographical features. Fifthly, some people think that animals migrate by following changes in temperature. And finally, there are people who suppose they migrate by following sound.
(30)
A．The weather gets hotter.
B．Telegraph wires stand still.
C．Swallows sit on telegraph wires.
D．People find the mystery of migration
The World of the Flat-footed Fly
George Poinar has been fascinated by amber, and the insects embedded in it, since childhood. Now a professor of entomology at the Berkeley Campus of the University of California, he has successfully combined these interests to produce Life in Amber, a scholarly and yet very readable book. In it he tells the story of this curious, almost magical substance and the unique record of fossilized life that became trapped and entombed in the sticky resin as it oozed from the forest trees of the ancient past.
Amber has been endowed with special worth from prehistoric times, Adornments of amber have been found that date back as far as 35,000 BC, and in 1701, King Frederick I of Prussia commissioned an entire room made of amber as a gift for Peter the Great of Russia. Historically that probably represented the peak of value for amber. Since then our appreciation of it as a decorative material worth its weight in gold has declined somewhat. In Victorian times amber beads had something of a renaissance as an adornment. It now holds greater value as a potential store of fossil DNA.
Scientific interest in amber has also fluctuated. The embedded small organisms, particularly insects but also frogs and feathers, have always been part of amber's allure. In the first century AD, Pliny noted that amber was the discharge of a pine-like tree, originated in the north and often contained small insects. It was not until the 19th century that collection of the amber flora and fauna really got under way. The largest hoard was of Baltic origin, amassed by Wilhelm Stantien, an innkeeper, and Moritz Becker, a merchant. They took their collecting seriously and used mining techniques to extract pieces of amber from clays of Tertiary age that had formed during the Eocene, 38 million years ago, in the Samland peninsula, near Kaliningrad (the former Kbnigsberg) on the Russian Baltic seaboard. Their efforts resulted in about 120,000 amber-embedded animal and plant fossils. These were housed in the Geological Institute Museum at Kbnigsberg University. Unfortunately, despite being dispersed for safety during the Second World War much of this amazing collection was lost.
Although the depth of this unique view of the insect life in Baltic forests of Eocene age is sadly no longer available in a single collection, we can see something of it. There are still large collections of Baltic amber in public museums around the world but even in total they do not amount to much more than that one unrepeatable collection. The Natural History Museum in London has a "mere" 25,000 specimens.
Popular misconceptions about amber exist; for example, suggesting that it is the fossilized resin of coniferous trees from the Baltic region, and that its abundance is the result of some unusual condition of these ancient trees. It is true that an astonishing amount of amber has been recovered from this region. However, the most likely candidate to have produced the Baltic amber is an araucariacean tree similar to the living Agathis from New Zealand, which secretes resin. This could well accumulate in this order of magnitude, given the geological time scale of hundreds of thousands, if not million of years. And, as Poinar discusses, the Baltic region was only one of many different areas, on a worldwide scale, from the Dominican Republic, which is his own favourite hunting ground, to China and Romania, that produced amber in Tertiary times. Furthermore, amber resin producing trees are shown to have an extended geological history extending back to Cretaceous times, more than 100 million years ago and possibly as far back as the Carboniferous (more than 300 million years ago ). Many of these older ambers have not been rigorously investigated with modem techniques but Poinar has collected all the available published knowledge on their biological content.
&n
A．Y
B．N
C．NG
