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芽孢杆菌生长到一定阶段,菌体内一端形成芽孢,另一端形成一种被称为伴孢晶体的蛋白质晶体。菌体破裂后释放出芽孢和伴孢晶体,伴孢晶体本身并无毒性,是毒素的前体。当昆虫吞食伴孢晶体后,在肠道内碱性环境条件和特定的蛋白酶的作用下,伴孢晶体变成毒素分子,能使小肠上皮细胞萎缩退化,昆虫停食,最后脱水死亡。科学家利用芽孢杆菌的这个特性,在实验室大量培养,制成生物农药,洒在农作物上,让害虫吃后中毒死亡。或利用基因工程技术,把芽孢杆菌的抗虫基因转到农作物体内,培育出抗虫品种。请根据上述材料回答下列问题: 大面积种植抗虫棉对该地区生态平衡会造成怎样的影响?①()②()。
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举一反三
【简答题】Task 1连线题 Task 1 Choose the proper packing materials for the listed goods.
【判断题】肉夹馍是唐代长安城中的美食。
A.
正确
B.
错误
【单选题】(单选)除元素外,其它合金元素溶于奥氏体后,均能增加过冷奥氏体的稳定性。()
A.
Co
B.
Cr
C.
Mn
【单选题】Task 2 Directions: This task is the same as Task 1. The 5 questions or unfinished statements are numbered 41 through 45. What is your favorite color? Do you like yellow, orange or red? If you do, you ...
A.
anyone can choose his color preference in his life
B.
no one can choose his color preference in his life
C.
anyone is born with his color preference
D.
no one is born with his color preference
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A.
银行存折
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银行传单
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D.
银行报表
【单选题】除 元素外,其它合金元素溶于奥氏体后,均能增加过冷奥氏体的稳定性。
A.
Co
B.
Cr
C.
Mn
D.
Ti
【单选题】Choose the correct meaning of each word.joint task
A.
common task
B.
unique task
C.
easy task
D.
united task
【单选题】除 A 元素外,其它合金元素溶于奥氏体后,均能增加过冷奥氏体的稳定性。
A.
Co
B.
Cr
C.
Mn
D.
Ti
【判断题】肉夹馍是唐代长安城中的美食。()
A.
正确
B.
错误
【单选题】Task 2 Directions: This task is the same as Task 1. The 5 questions or unfinished statements are numbered 41 through 45. What is your favorite color? Do you like yellow, orange or red? If you do, you ...
A.
anyone can choose his color preference in his life
B.
no one can choose his color preference in his life
C.
anyone is born with his color preference
D.
no one is born with his color preference
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