题目内容
Supporting groups ___ all over the country. Many people were excited about it.
A. sprang B. sprang up C. spring D. springs up
B
Now let’s look ourselves as a species in relation to ecosystem balance.Modern scientists believe that humankind, like other animals, evolved(进化) through millions of years of changes and adaptations to the environment and that our most direct evolutionary ancestor was probably an earlier species of the primate(monkey, ape) group. Despite this similarity with other creatures, however, the evolution of humankind differs from that of other species in one important and unique way.
In other species, evolution has led to specialization, both in the species abilities and in its place within the environmental structure. For example, the giraffe is much adapted to feeding on treetops, but it is also specialized and thus limited to feeding on trees and shrubs. Only with great difficulty can it bend down to graze on the ground. Similarly, the anteater is extremely well adapted to eating ants but is unable to catch or eat other animals. The same is true for countless other species.
For humankind it is opposite. Our evolution had led to a very generalized ability. Our highly developed intelligence and ability to make and handle tools mean that we can do almost anything. Humans evolved in such a way that we are able to move into every environment on Earth and even into space. No natural competitor offers great resistance, and other natural enemies such as disease have been controlled.
Said another way, we see in humankind a great imbalance between biological potential and environmental resistance. The result is the rapidly increasing world population, frequently referred to as the population explosion. Further, to support our growing population, natural ecosystems are being increasingly displaced by human habitations, agriculture, and other human supporting activities.
【小题1】From the passage we can infer that in the course of evolution _______.
A.humankind is very important to earlier species, such as the primate group |
B.human beings are limited by the environment while animals are not |
C.human beings become more and more different from each other |
D.humankind has experienced a generalization rather than specialization in ability |
A.monkeys and anteaters | B.tigers and apes |
C.apes and monkeys | D.monkeys and giraffes |
A.increase the population |
B.resist natural offers |
C.go to the moon |
D.cure all diseases |
A.the population explosion |
B.the destruction of human habitations |
C.the growth of natural ecosystem |
D.the specialization of humans |
A microscope is a useful instrument for observing small objects. By producing a bigger image, the microscope reveals details that are undetectable to the naked eye(裸眼).
Before using the microscope, please read the instructions below.
CAUTION: Microscopes are both delicate and expensive and must be handled with care.
1. Always carry the microscope with two hands — one supporting the base and the other on the arm.
2. Avoid stretching the wire of the lamp across a walkway.
3. Keep the stage clean and always use a glass slide for specimens(样本).
4. To avoid crushing the glass slide when focusing, begin with the lens close to the specimen and gradually back off to focus.
5. Keep the microscope covered to prevent the dust while it is being stored.
HOW TO USE THE MICROSCOPE:
1. Plug(接通电源) in the lamp.
2. Place a sample of what you wish to observe on a slide.
3. Adjust the mirror so it reflects light from the room up into the objective lens. When the mirror is correctly adjusted, a complete circle of light iwll appear when you look through the eyepiece.
4. Place your slide with the specimen directly over the center of the glass circle on teh stage. If it is a wet slide, be sure the bottom of the slide is dry.
5. With the LOW POWER objective leans placed over the slide, use the coarse focus knob to lower the lens to the lowest point.
6. Look through the eyepiece with one eye while closing the other eye. Slowly raise the lens until teh focus is relatively clear.
7. Use the fine focus knob to fine -tune(微调)the focus.
8. Without changing the focus knobs, switch to the HIGH POWER objective lens. Once you have switched to HIGH POWER, use only the fine focus knob to make the image sharper.
【小题1】Which of the following is the correct way to use a microscope according to the text?
A.Use one hand to carry the microscope |
B.Place a sample directly on the clean stage |
C.When stored, the microscope should be adjusted. |
D.Look through the eyepiece with one eye. |
A.Switch to objective lens. | B.Adjust the mirror. |
C.Look through the eyepiece. | D.Place the hair on a glass slide. |
A.after correctly adjusting the mirror |
B.while looking at the specimen on a glass slide |
C.after slowly raising the objective lens |
D.before positioning the mirror correctly |