听力原文：If you can't finish this assignment, please let me ..

第1题

In the English language, what are the aspects that are most likely to interfere with communication?

A、stress

B、rhythm

C、pitch

第2题

听力原文：In American industry, there's still relatively little job mobility. After all, getting an employment is not an easy job nowadays.

(27)

A．American workers tend to stay in one job.

B．Crop dusting jobs in American are few.

C．The mob moved very slowly.

D．Their relatives live in mobile home.

点击查看答案

第3题

听力原文：There are not enough cases for so many suits, so we have to rearrange those cases. We can fit one more suit into the case, can't we？

(26)

A．This case can hold more suits than that one.

B．We can't find the other case of suits.

C．Can this case fit in with the others？

D．Can't we put another suit into the case？

点击查看答案

第4题

听力原文：It is an intricate work that needs searching information on Internet. He can't do this work without a laptop or a desktop.

(29)

A．He can work better without a computer.

B．He is working with a new computer.

C．He has never used a computer in his work.

D．He needs a computer for his work.

点击查看答案

第5题

This view may be correct: it has the advantage that the currents are driven by temperature differences that themselves depend on the position of the continents. Such a back-coupling, in which the position of the moving plate has an impact on the forces that move it, could produce complicated and varying motions.

On the other hand, the theory is implausible because convection does not normally occur along lines, and it certainly does not occur along lines broken by frequent offsets or changes in direction, as the ridge is. Also it is difficult to see how the theory applies to the plate between the Mid-Atlantic Ridge and the ridge in the Indian Ocean. This plate is growing on both sides, and since there is no intermediate trench, the two ridges must be moving apart. It would be odd if the rising convection currents kept exact pace with them. An alternative theory is that the sinking part of the plate, which is denser than the hotter surrounding mantle, pulls the rest of the plate after it. Again it is difficult to see how this applies to the ridge in the South Atlantic, where neither the African nor the American plate has a sinking part.

Another possibility is that the sinking plate cools the neighboring mantle and produces convection currents that move the plates. This last theory is attractive because it gives some hope of explaining the enclosed seas, such as the Sea of Japan. These seas have a typical oceanic floor, except that the floor is overlaid by several kilometers of sediment. Their floors have probably been sinking for long periods.

It seems possible that a sinking current of cooled mantle material on the upper side of the plate might be the cause of such deep basins. The enclosed seas are an important feature of the earth's surface and seriously require explanation because, in addition to the enclosed seas that are developing at present behind island arcs, there are a number of older ones of possibly similar origin, such as the Gulf of Mexico, the Black Sea, and perhaps the North Sea.

According to the traditional view of the origin of the ocean basins, which of the following is sufficient to move the continental plates？ ______

A．Increases in sedimentation on ocean floors.

B．Movement of mid-ocean ridges.

C．Sinking of ocean basins.

D．Differences in temperature under oceans and continents.

点击查看答案

第6题

Species interdependence in nature confers many benefits on the species involved, but it can also become a point of weakness when one species involved in the relationship is affected by a catastrophe. Thus, flowering plant species dependent on insect pollination, as opposed to self- pollination or wind pollination, could be endangered when the population of insect-pollinators is depleted by the use of pesticides.

In the forests of New Brunswick, for example, various pesticides have been sprayed in the past 25 years in efforts to control the spruce budworm, an economically significant pest. Scientists have now investigated the effects of the spraying of Matacil, one of the anti-budworm agents that is least toxic to insect-pollinators. They studied Matacil's effects on insect mortality in a wide variety of wild insect species and on plant fecundity, expressed as the percentage of the total flowers on an individual plant that actually developed fruit and bore seeds. They found that the most pronounced mortality after the spraying of Matacil occurred among the smaller bees and one family of flies, insects that were all important pollinators of numerous species of plants growing beneath the tree canopy of forests. The fecundity of plants in one common indigenous species, the red-osier dogwood, was significantly reduced in the sprayed areas as compared to that of plants in control plots where Matacil was not sprayed. This species is highly dependent on the insect-pollinators most vulnerable to Matacil. The creeping dogwood, a species similar to the red-osier dogwood, but which is pollinated by large bees, such as bumblebees, showed no significant decline in fecundity. Since large bees are not affected by the spraying of Matacil, these results add weight to the argument that spraying where the pollinators are sensitive to the pesticide used decreases plant fecundity.

The question of whether the decrease in plant fecundity caused by the spraying of pesticides actually causes a decline in the overall population of flowering plant species still remains unanswered. Plant species dependent solely on seeds for survival or dispersal are obviously more vulnerable to any decrease in plant fecundity that occurs, whatever its cause. If, on the other hand, vegetative growth and dispersal (by means of shoots or runners) are available as alternative reproductive strategies for a species, then decreases in plant fecundity may be of little consequence. The fecundity effects described here are likely to have the most profound impact on plant species with all four of the following characteristics, a short life span, a narrow geographic range, an incapacity for vegetative propagation, and a dependence on a small number of insect- pollinator species. Perhaps we should give special attention to the conservation of such plant species since they lack key factors in their defenses against the environmental disruption caused by pesticide use.

Which of the following best summarizes the main point of the passage？ ______

A．Species interdependence is a point of weakness for some plants, but is generally beneficial to insects involved in pollination.

B．Efforts to control the spruce budworm have had deleterious effects on the red-osier dogwood.

C．The use of pesticides may be endangering certain plant species dependent on insects for pollination.

D．The spraying of pesticides can reduce the fecundity of a plant species, but probably does not affect its overall population stability.

点击查看答案

第7题