某农户计划种植黄瓜和韭菜,种植面积不超过50亩,投入资金不超过54万元,假设种植

题型:填空题

问题:

某农户计划种植黄瓜和韭菜,种植面积不超过50亩,投入资金不超过54万元,假设种植黄瓜和韭菜的产量、成本和售价如下表:
 
年产量/亩
年种植成本/亩
每吨售价
黄瓜
4t
1.2万元
0.55万元
韭菜
6t
0.9万元
0.3万元
为使一年的种植的总利润最大,那么黄瓜和韭菜的种植面积分别为________.
考点:简单线性规划问题(用平面区域表示二元一次不等式组)
题型:填空题

需另煎的药是

A.生石膏
B.徐长卿
C.葶苈子
D.羚羊角
E.阿胶

题型:填空题

强夯加固地基的过程包括以下( )阶段。

A.能量转化,土体结构

B.恢复阶段

题型:填空题

阅读理解。

     The need to feed a growing population is putting much pressure on the world's supply of water. With

97% of the world's water too salty to be drunk or used in agriculture, the worldwide supply of water needs

careful management, especially in agriculture.

     Although the idea of a water shortage seems strange to someone fortunate enough to live in a high rainfall

country, many of the world's agricultural industries experience constant water shortages. Although dams

can be built to store water for agricultural use in dry areas and dry seasons, the costs of water redistribution

(重新分配) are very high. Not only is there the cost of the engineering itself, but there is also an environmental

cost to be considered. Where valleys are flooded to create dams, houses are lost and wildlife homes destroyed.

Besides, water may flow easily through pipes to fields, but it cannot be transported from one side of the world

to the other. Each country must therefore rely on the management of its own water to supply its farming

requirements.

     This is particularly troubling for countries with agricultural industries in areas dependent on irrigation. In

Texas, farmers' overuse of irrigation water has resulted in a 25% reduction of the water stores. In the Central

Valley area of southwestern USA, a huge water engineering project provided water for farming in dry valleys,

but much of the water use has been poorly managed.

     Saudi Arabia's attempts to grow wheat in desert areas have seen the pumping of huge quantities of

irrigation water from underground reserves. Because there is no rainfall in these areas, such reserves can only

decrease, and it is believed that fifty years of pumping will see them run dry.

1. From the first two paragraphs we learn that _______.

A. much of the world's water is available for use

B. people in high rainfall countries feel lucky

C. water can be easily carried through pipes across the world

D. the costs of water redistribution should be considered .

2. Which of the following is true?

A. The underground water in Saudi Arabia might run out in 50 years.

B. Most industries in the world suffer from water shortages.

C. The water stores in Texas have been reduced by 75%.

D. Good management of water use resulted from the project in the Central Valley.

3. The text is mainly about _______.

A. water supply and increasing population

B. water redistribution and wildlife protection

C. water use management and agriculture

D. water shortages and environmental protection

4. What is most likely to be discussed in the paragraph that follows?

A. Approaches to handling the pressure on water supply.

B. Ways to reduce the costs of building dams.

C. Measures to deal with worldwide water shortages.

D. Steps to improving water use management

题型:填空题

下列神经鞘瘤与神经纤维瘤的鉴别要点,错误的是()。

A.神经鞘瘤来源于神经鞘细胞;神经纤维瘤来源于神经束膜、外膜或内膜等支持细胞

B.神经鞘瘤最常见部位为正中神经干、尺神经干、坐骨神经及桡神经;神经纤维瘤可发生于神经末梢或神经干的任何部位

C.神经鞘瘤多为单发;神经纤维瘤可单发或多发,以多发者为常见

D.神经鞘瘤之神经纤维穿过瘤体;神经纤维瘤之神经纤维并不穿过肿瘤组织

E.神经鞘瘤分为中央型和边缘型;神经纤维瘤内可有脂肪、毛细血管等组织

题型:填空题

一健康的人若适度增加进食糖和食盐,则他排出的尿中所含葡萄糖和盐分的量是()

A.两者都较多

B.两者的含量均未变

C.含糖较多,含盐量不变

D.不含糖,但含盐量增加

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