Question

    Not many organisms can survive in this severe environment, the Sahara Desert, where daytime temperatures can reach 140 degrees Fahrenheit. But an insect called the Saharan silver ant grows well. They rush out onto the sand from their protected nests to gather up the bodies of insects that have died from the heat.

“The hotter the day, the more insect bodies they will find. The more food they have.” said Sarah Pfeffer, an animal behaviorist at Ulm University in Germany. She says that to avoid sinking into the Saharan sand, where they could meet the same fate（命运）as their lunch, silver ants have to be fast.

To document just how quickly the ants move, Pfeffer and her colleagues set up high-speed cameras above a channel between the entrance to the hungry ants’ nest and a food source. The researchers recorded top speeds approaching 35 inches per second.“But if you really look at how big the animals are and you calculate the body length per second, you will come up with a walking speed that is an astonishing 108 body-lengths per second.”That figure makes them the fastest known ant on the planet. By comparison, cheetahs(猎豹）top out at about 16 body lengths per second. The videos showed how the ants achieve such amazing speeds. As they accelerate, their leg movements become synchronized(同步). They increase their running length by bringing all six feet off the sand at once, which Pfeffer describes as a gallop. “Really all legs are lifted from the ground. They are in the air, but it’s not jumping. It’s a very smooth run that they have.”

A closely related ant called Cataglyphis fortis only reaches about 24 inches per second, or two-thirds of the silver ant's max.

The Saharan silver ants' speeds may be impressive, but two insects are even faster. The Califormia coastal mite (壁虱) and the Australian tiger beetle, both of which also grow well at near-deadly temperatures. It seems that to beat the heat, it pays to be fleet.

1.What does the underlined word "they" refer to?

A.The insects. B.The silver ants.

C.Pfeffer and her colleagues. D.The high-speed cameras.

2.How long is a Saharan silver ant?

A.About 0.14 inches. B.About 0.08 inches.

C.About 0.22 inches. D.About 0.32 inches.

3.How do the ants accelerate while running?

A.By jumping smoothly. B.By lifting all their legs.

C.By sinking into the sand. D.By flying in the air.

4.Why does the author mention another two animals in the last paragraph?

A.To introduce two speedy animals.

B.To present the near-deadly environment.

C.To show high temperature makes fast speed.

D.To indicate silver ants rank third in speed.

Answer

1.B

2.D

3.B

4.C

【解析】

这是一篇说明文。文章介绍能在撒哈拉沙漠的环境中生存的一种叫做“撒哈拉银蚁”的昆虫。

1.词义指代题。根据第二段中She says that to avoid sinking into the Saharan sand, silver ants have to be fast.“她说，为了避免陷入撒哈拉沙漠，银蚁必须行动迅速。”由此可知，where they could meet the same fate（命运）as their lunch,中划线词they指代的是“silver ants”。故选B。

2.计算题。根据第三段中The researchers recorded top speeds approaching 35 inches per second.“But if you really look at how big the animals are and you calculate the body length per second, you will come up with a walking speed that is an astonishing 108 body-lengths per second.”“ 研究人员记录的最高速度接近每秒35英寸。“但如果你真正观察动物的大小,然后你计算每秒钟的身体长度,你就会得到一个速度,每秒钟108个身体的长度。”由此可知，蚂蚁的长度是35/108=0.32”，故选D。

3.细节理解题。根据第三段中Really all legs are lifted from the ground. They are in the air, but it’s not jumping. It’s a very smooth run that they have.“所有的腿都从地上抬起。它们在空中，但它不跳。这是一个非常平稳的奔跑。”由此可知，蚂蚁通过抬起他们所有的腿在奔跑时加速。故选B。

4.推理判断题。根据最后一段The Saharan silver ants' speeds may be impressive, but two insects are even faster. The Califormia coastal mite (壁虱) and the Australian tiger beetle, both of which also grow well at near-deadly temperatures. It seems that to beat the heat, it pays to be fleet.“撒哈拉的银蚂蚁的速度可能令人印象深刻,但两种昆虫甚至更快。加州的海岸螨和澳大利亚的老虎甲虫,这两种都在近乎致命的温度下生长得很好。似乎是为了战胜炎热,成为舰队是值得的。”由此可知，作者在最后一段提到了另外两只动物是为了显示高温使速度快速。故选C。