题干

下列选项中,对种群密度影响最严重的是(   )
编号
生态系统
采收对象
现有生物量
年增长率/%
年采收量

马尾松林
马尾松
20000m3
2
1000m3

淡水湖泊
鲰鱼
10000kg
34
3600kg

山地
甘草
1000kg
20
300kg

滩涂
沙蚕
10000kg
30
500kg

A:①

B:②

C:③

D:④

上一题 下一题 0.0难度 选择题 更新时间:2017-11-25 01:03:27

答案(点此获取答案解析)

C

同类题5

根据短文内容,选择正确答案。

When they saw I didn't move, they quickly built a platform(平台) next to my head, and an official (官员) climbed up there to speak to me. Although I could not understand his language, I understood that they would be friendly towards me---if I did not try to harm (伤害) them. By now I was very hungry, so I used sign language to ask the official for food. He seemed to understand me, because they put ladders(梯子) against my sides and little men climbed up with baskets of food and drink. They were surprised at how much I could eat and drink. In just one mouthful(一口) I ate three of their meat dishes and three of their loaves of bread. I drank two of their barrels (桶)of wine, and was still thirsty, because that was only half a litre (1升). While they were bringing me food, I wondered whether(是否) to pick up some of the little men and throw them to their death. But I was afraid they would shoot at me again, and anyway I was thankful for their kindness in giving me food and drink, so I did not move.

After some time, another official climbed up to the platform and spoke to me. From his signs I understood that they were going to move me. The King of this country(which was called Lilliput) had ordered his people to carry me to the capital city. I made signs to ask whether I could be untied(松绑),but the official politely refused.

While I was eating, they had prepared a platform to carry me. The people of Lilliput are very clever with their hands. For me, five hundred men built a special wooden platform with twenty-two wheels. One thousand, five hundred of the King's largest horses pulled me to the capital. I did not know about any of this, because they had put some sleeping pills (安眠药) in my wine, and I was in a deep sleep.