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问题 不定项选择

如图所示，电源、灯泡与螺线管组成了一个闭合电路，待电路稳定后，小灯泡有一定的亮度。现将一与螺线管等长的软铁棒沿管的轴线迅速插入螺线管内，则在插入过程中小灯泡的亮度将

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A．变亮

B．变暗

C．一直不变

D．先变亮后变暗

答案

答案：B

单项选择题

Should we care if over 150 known species of animals have (91) from the earth in the last fifty years Should we be concerned that there are (92) thousands of species whose very existence is (93) endangered—largely because of our activities (94) , after all, is the natural end of populations. Species are born, then (95) , and then die. Some live a (96) time, perhaps millions of years; some die more quickly. We have (97) the extinction of many species we know about, and we have undoubtedly sealed the (98) of others. In fact, there are undoubtedly many other species that have lived among us during our time on earth, but that have disappeared as a (n) (99) of our activities without our ever having known they existed.
It is hard to explain the rationale of many of us who are concerned about such matters. I have never seen a sea whale, (100) I don’t want them to become extinct. Moreover, I felt this way long before I understood anything about how they might be an important part of an ecosystem. Possibly such feelings merely reflect the cultural attitude that it is "nice" to wish other living things well; thus, the attitude is (101) . I feel nice.
There are, of course, more rational reasons for (102) the extermination of any species. For one thing, the kind of attitude that encourages or sanctions the destruction of other species is a threat (103) our own wellbeing. If such an attitude exists, we ourselves might (104) victim to it. living things (including us) might be expected to fare better where there is (105) for life. The extinction of other species could also threaten us (106) by simplifying the system of which we are a part or by destroying parts of the ecosystem (107) which we directly rely. For example, if we continue to poison the oceans (108) we are willing to believe only a few bottom dwellers are affected, we might (109) overstep some critical threshold and trigger the wholesale death of plankton, thus finding ourselves without a major (110) of the world’s food and with our oxygen supplies dwindling.

A．gain

B．enter

C．become

D．fall
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单项选择题

根据合同法律制度规定，技术合同的一方当事人延迟履行主要义务，对方当事人有权主张解除合同的条件是( )。

A．经催告后30日内仍未履行的
B．经催告后1个月后仍未履行的
C．在催告通知书中附有履行期限，在该期限届满后仍未履行的
D．在催告通知书中附有履行期限，在该期限届满后30日内仍未履行的
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