简述菜蚜的主要种类与危害习性。

题型:问答题 简答题

问题:

简述菜蚜的主要种类与危害习性。

考点:农学植物保护技术植物保护技术题库
题型:问答题 简答题
已知直线l:
2x
a
+
y
b
=2(a>2,b>1)
与曲线x2+y2-2x-2y+1=0相切且直线l交与x轴交于A点,交y轴于点B,则△AOB面积的最小值为______.
题型:问答题 简答题

下列免疫活动中,属于特异性免疫的是()

A.消化液将食物中的细菌杀死

B.抗体抵抗天花病毒

C.溶菌酶杀死细菌

D.白细胞吞噬病菌

E.呼吸道黏膜能黏附细菌

题型:问答题 简答题

胸痹心痛的主要病因有()

A.年老体虚

B.情志失调

C.寒邪内侵

D.药物中毒

E.饮食不节

题型:问答题 简答题

阅读理解。

     "Soon, you're going to have to move out!" cried my neighbor upon seeing the largest tomato plant

known to mankind, or at least known in my neighborhood.

     One tiny 9-inch plant, bought for $1.25 in the spring, has already taken over much of my rose bed,

covering much of other plants, and is well on its way to the front door.

     Roses require a good deal of care, and if it weren't for the pleasure they give, it wouldn't be worth

the work. As it is, I have a garden full of sweet-smelling roses for most of the year. Bushes must be

pruned(剪枝) in early spring, leaving ugly woody branches until the new growth appears a few weeks

later. It was the space available in the garden that led me into planting just one little tomato plant. A big

mistake.

     Soil conditions made just perfect for roses turn out to be even more perfect for tomatoes. The daily

watering coupled with full sun and regular fertilizing have turned the little plant into a tall bush. The cage

I placed around it as the plant grew has long disappeared under the thick leaves.

     Now the task I face in harvesting the fruit is twofold: First, I have to stand on my head, and once

found I have to reach down and under, pick the tomatoes and withdraw (缩回) my full fist without

dropping the prize so dearly won. I found tow full-blown white roses completely hidden as I picked

tomatoes in June. But they were weak and the leaves already turned yellow for lack of light.

     Here I am faced with a painful small decision. To tear up a wonderful and productive tomato plant

that offers up between ten and twenty ripe sweet tomatoes each day or say goodbye to several

expensive and treasured roses. Like Scarlet in Gone with the Wind, I'll think about that tomorrow.

1. The writer decided to plant the tomato just because ____.  

A. it cost little  

B. the soil conditions were proper 

C. the space left could be used 

D. the roses were growing too fast

2. What are the requirements for the healthy growth of rose? 

A. Enough care and right soil conditions. 

B. Frequent pruning and fertilizing. 

C. Tomato plants grown alongside. 

D. Cage placed around the roots.

3. By saying "the prize so dearly won" in Para.5, the writer wants to ____.   

A. show the difficulty in picking the tomatoes 

B. show the hardship of growing the roses 

C. express her liking for the roses. 

D. express her care for the tomatoes

题型:问答题 简答题

读我国某地区等高线图,回答下列小题。

下面四幅地形剖面图中,与等高线图中沿XY的剖面相吻合的是()

A.

B.

C.

D.

更多题库