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During the past 1,000 years, the climates of the British Isles and continental Europe have undergone various episodes of change. It has long been believed that the demographic and economic expansion of Europe between the tenth and thirteenth centuries coincided with, and was perhaps encouraged by, a period of relative warmth, favorable to the expansion of cereal cultivation and the colonization of previously inhospitable environments. This benign phase, although variously dated, was seen to lie between a period of less favorable conditions in the late and post-Roman centuries and the so-called Little Ice Age of the early modem period, which was characterized by an overall cooling of the climate and, in particular by an increased severity of winters. Climatic deterioration was seen to have begun by circa 1300, presaged by an increase in stormy conditions in Europe, and associated with runs of wet and cool summers and the widespread harvest failures and livestock mortality of the years 1315-1322.
The integrity of the so-called medieval warm period, once considered a global phenomenon, has, however, been called into question by recent paleoenvironmental research. The picture that now emerges is of a less coherent and perhaps more geographically restricted phase—variously dated —of relative warmth, when temperatures in northwest Europe and the North Atlantic area were on average higher than in the post-Roman and early modern periods, although probably not warmer than in the late twentieth century. Some types of evidence, including the records of the advance and retreat of Alpine glaciers, suggest that the later fourteenth and early fififteenth centuries may have seen a notable climatic downturn, followed by a temporary amelioration around1500, before renewed cooling into the Late Maunder Minimum period of 1675-1715. The relationship between glacial advance or retreat and temperature is, however, complex. A study of winter severity in central Europe during the fourteenth century found no clear trend, rather the alternation of runs of cold and mild winters.with the most sustained period of severe winters falling in the period 301-1328. English documentary sources have been used to suggest a cooling trend from circa 1240-1340, with a subsequent amelioration followed by renewed cooling from circa 1510, but the sporadic nature of this data series necessitates caution. A long-term cooling trend in the northern hemisphere between the twelfth/thirteenth and the seventeenth centuries does, however emerge from a plethora of sources, including tree-ring data, the study of lake and ocean sediments, and analysis of Greenland ice cores.
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[数学 ]【新版】冲分救命题 -11998
The integers a, b, and c are positive, and a>b>c. When a, b, and c are divided by 3, the remainders are 0, 1, and 1, respectively.
[数学 ]【新版】冲分救命题 -11997
For all positive even integers n. n* represents the product of all even integers from 2 to n, inclusive. For example, 12*=12×10×8×6×4×2. What is the greatest prime factor of 20*+22*?
[数学 ]【新版】冲分救命题 -11996
[数学 ]【新版】冲分救命题 -11995
[数学 ]【新版】冲分救命题 -11994
In a game, the cards in a certain deck are distributed to players one at a time until each player has the same number of cards and there are not enough cards left in the deck to distribute one more card to each player. The number of cards in the deck is between 60 and 100. If the cards in the deck are distributed o 5 players, 2 cards will be left in the deck. If the cards in the deck are distributed to 6 players, 4 cards will be left in the deck. If the cards in the deck are distributed to 7 players, how many cards will be left in the deck?
[数学 ]【新版】冲分救命题 -11993
Let a be the greatest integer such that is a factor of 1,500, and let b be the greatest integer such that is a factor of 33,333,333. Which of the following statements are true? Indicate all such statements.
[数学 ]【新版】冲分救命题 -11992
A set consists of all three-digit positive integers with the following properties.Each integer is of the form JKL,where J,K,and I are digits;all the digits are nonzero;and the two-digit integers JK and KL are each divisible by 9.How many integers are in the set?
[数学 ]【新版】冲分救命题 -11991
[数学 ]【新版】冲分救命题 -11990
The number of children in a certain family is a prime number less than 10. The number of boys in the family is greater than the number of girls, and the number of boys is a prime number. If at least 1 of the children in the family is a girl, which of the following could be the number of boys in the family?Indicate all such numbers.
[数学 ]【新版】冲分救命题 -11989
[数学 ]【新版】冲分救命题 -11988
x and y are integers.
[数学 ]【新版】冲分救命题 -11987
x and y are integers.
[数学 ]【新版】冲分救命题 -11986
a and b are distinct odd prime numbers.
[数学 ]【新版】冲分救命题 -11985
When the integer n is divided by 33, the remainder is 24. Which of the following must be a divisor of n?
[数学 ]【新版】冲分救命题 -11984
4.What is the length of an edge of the smallest solid cube that can be made by placing together solid rectangular blocks of size 7 by 6 by 3?
[数学 ]【新版】冲分救命题 -11983
Light travels at approximately 186,000 miles per second.Which of the following is closest to the number of miles that light travels in 3 hours.
[数学 ]【新版】冲分救命题 -11982
The number n is the least positive integer for which 108n is the square of an intege
[数学 ]【新版】冲分救命题 -11981
The number n is the least positive integer for which 108n is the square of an intege
[数学 ]【新版】冲分救命题 -11980
If x=2y+1, and y=2w, where w, x, and y are integers, which of the following must be an odd integer?
[数学 ]OG -11979
If x=2y+1, and y=2w, where w, x, and y are integers, which of the following must be an odd integer?
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