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【多选题】
判断下列集合对所给的代数运算是否封闭 。
A.
整数集合 Z 和普通的减法运算；
B.
非零整数集合 Z* 和普通的乘法运算；
C.
集合 A={x|x ∈ N ∧x 为奇数 } 和普通的加法及乘法运算；
D.
n 阶实矩阵集合 M n (R) 关于 矩阵加法和矩阵乘法运算；
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【单选题】When did most farmers have to pay their debts?
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When crop failure caused depression.
B.
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【单选题】作功顺序为1—3—4—2的发动机，在第三缸活塞压缩上止点时，可以检查调整（ ）间隙。
A.
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【单选题】根据城建税规定，下列说法正确的是（ ）
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【单选题】In some countries in which there is very little rain at any time, the farmers have to water their fields. Irrigation is easy enough if there is a great river near the crops and if there is plenty of w...
A.
the problems caused by river water
B.
the necessity to irrigate the field
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the water shortage in some countries
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【简答题】In some countries in which there is very little rain at any time, the farmers have to irrigate their fields. Irrigation is easy enough if there is a great river near the crops, and if there is plenty ...
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进口环节增值税纳税人同时也是城建税纳税人
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【单选题】To label their product as organic， farmers have to obtain a certificate showing that no __________chemicals have been used to kill pests on the farm for two years.
A.
tragic
B.
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C.
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D.
nominal
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相关题目：
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A.
3缸的进、排气门和4、2缸的进气门
B.
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C.
3缸的进、排气门和4缸的排气门和1缸的进气门
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3 、 1 缸的进、排气门和 4 、 2 缸的进气门
B.
1 、 4 缸的进气门和 2 、 3 的排气门
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【单选题】When did most farmers have to pay their debts?
A.
When crop failure caused depression.
B.
When the autumn harvest had just been completed.
C.
When the wheat prices became increasingly high.
D.
As soon as the Winnipeg Grain Exchange demanded payment:
查看完整题目与答案
【单选题】作功顺序为1—3—4—2的发动机，在第三缸活塞压缩上止点时，可以检查调整（ ）间隙。
A.
3 、 1 缸的进、排气门和 4 、 2 缸的进气门
B.
1 、 4 缸的进气门和 2 、 3 的排气门
C.
3 缸的进、排气门和 4 缸的排气门和 2 缸的进气门
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D． 3 缸的进、排气门和 4 缸的排气门和 1 缸的进气门
查看完整题目与答案
【单选题】根据城建税规定，下列说法正确的是（ ）
A.
自 2010 年 12 月 1 日起，外商投资企业应依法缴纳城建税
B.
进口环节增值税纳税人同时也是城建税纳税人
C.
城建税实行行业差别税率
D.
城建税的计税依据是纳税人缴纳的增值税、消费税以及滞纳金和罚款
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【单选题】In some countries in which there is very little rain at any time, the farmers have to water their fields. Irrigation is easy enough if there is a great river near the crops and if there is plenty of w...
A.
the problems caused by river water
B.
the necessity to irrigate the field
C.
the water shortage in some countries
D.
the canals carrying water to fields
查看完整题目与答案
【简答题】In some countries in which there is very little rain at any time, the farmers have to irrigate their fields. Irrigation is easy enough if there is a great river near the crops, and if there is plenty ...
查看完整题目与答案
【单选题】According to the passage， what did the farmers have to do with the coming of mechaniza-tion of agriculture? 查看材料
A.
Many of them had to leave their farmland for industrial centers．
B.
They stuck to their farm work．
C.
They refused to use machines．
D.
They did their best to learn how to use the machines．
查看完整题目与答案
【单选题】根据城建税规定，下列说法正确的是( )
A.
城建税的计税依据是纳税人缴纳的增值税、消费税以及滞纳金和罚款
B.
自2010年12月1日起，外商投资企业应依法缴纳城建税
C.
城建税实行行业差别税率
D.
进口环节增值税纳税人同时也是城建税纳税人
查看完整题目与答案
【单选题】To label their product as organic， farmers have to obtain a certificate showing that no __________chemicals have been used to kill pests on the farm for two years.
A.
tragic
B.
toxic
C.
notorious
D.
nominal
查看完整题目与答案