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【简答题】

榆树枯萎病的发病规律有:

题目标签:枯萎病规律榆树
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参考解析:
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【多选题】胡椒枯萎病在的传播途是( )

A.
带病种苗调运进行远距离传播。
B.
种子带毒传播。
C.
土壤传播
D.
地面流水传播
E.
农具传播
F.
割蔓传播

【单选题】An elm in our backyard(7)the blight (枯萎病) this summer and dropped stone dead, leafless, almost overnight. One weekend(8)was a normal-looking elm, maybe a little bare in spots but(9)alarming, and the n...

A.
There are so many new books about dying that there are now special shelves set aside for them in bookshops, along with the health-diet and home-repair paperbacks. Some of them are so(1) with detailed information and step-by-step instructions for performing the function, that you’d think this was a new sort of(2)which all of us are now required to learn. The strongest impression the casual reader gets is that proper dying has become an extraordinary,(3)an exotic experience, something only the specially trained can do.
B.
(4), you could be led to believe that we are the only(5)capable of being aware of death, and that when the rest of nature is experiencing the life cycle and dying, one generation after(6), it is a different kind of process, done automatically and trivially, or more "natural", as we say.

【单选题】边际产量递减规律所研究的问题是( )

A.
其他生产要素不变,一种生产要素变动时对产量的影响
B.
各种生产要素同时变动对产量的影响
C.
两种生产要素同时变动对产品的影响
D.
一种生产要素不变,其他生产要素变动时对产量的影响