[填空题]A vegetable crop expert advised ______ (将这些蔬菜放置在可以接受八到十小时日晒的地方) a day.

[填空题]A vegetable crop expert advised ______ (将这些蔬菜放置在可以接受八到十小时日晒的地方) a day.

[简答题]GM crop

[单项选择]蔬菜应现烧现吃，放置过久的熟蔬菜会出现（）
A. 蛋白质分解
B. 咸度增加
C. 亚硝酸盐增加
D. 水分增加
E. 调味品分解

[单项选择]蔬菜应现烧现吃，放置过久的熟蔬菜会引起（）
A. 蛋白质分解
B. 咸度增加
C. 亚硝酸盐增加
D. 水分减少
E. 调味品分解

[单项选择]蔬菜应现烧现吃，放置过久的熟蔬菜会引起下列哪种变化（）。
A. 水分减少
B. 蛋白质分解
C. 亚硝酸盐增加
D. 咸度增加
E. 调味品分解

[简答题]expert statistical group

[单项选择]A. Crop production became increasingly specialized.
B. Economic depressions cut the prices of farm products.
C. New banking laws made it easy to buy farmland.
D. America increased its agricultural imports.

[单项选择]一项研究发现，新鲜蔬菜分别常温、冷藏放置两天后，亚硝酸盐含量会升高，并不同程度高出国家标准限值，对人的身体会造成轻到重度的中毒情况。对此，研究人员将5种久置的蔬菜用果蔬洗涤剂浸泡5到10分钟，用清水冲洗干净后，又测试了亚硝酸盐含量。结果显示，蔬菜中亚硝酸盐的含量明显降低，并很快降低到安全值。因此研究人员认为，久置蔬菜经果蔬洗涤剂清洗后可放心食用。 下面哪项如果为真，最能削弱研究人员的实验结论
A. 5种蔬菜中亚硝酸盐含量不同
B. 果蔬洗涤剂中的化学物质会破坏蔬菜的口感
C. 实验中亚硝酸盐含量只是短时间内降低，很快就恢复到超标状态
D. 在清水中浸泡20分钟以上也能达到在实验中同样的效果

[填空题]The United States produced higher crop harvests before roads took away land and pollution affected crops.

[填空题]
They are giant geometric patterns, which appear over-night in a field of crops. Many people believe that they are made by aliens. (46) . "Crop circle", as the mysterious patterns are called, became a hot phrase this month.
(47) . It’s believed to be the world’s first three-dimensional crop circle. The giant crop circle gives an impression of looking down on skyscrapers from above. (48) . Crop circles were first widely noticed in the late 1970s as many mysterious circles began appearing-in crop fields throughout the English countryside. People were intrigued by these giant patterns. They were huge (at least tens of meters in diameters) and popped up over-night. (49) .
Various scientific and pseudo-scientific explanations were put forward to explain the phenomenon. Some hold that they were left by alien spaceships. Others say that they are simply an elaborate prank. (50)