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【简答题】
The world’s population is increasing at an ever-fast rate, with severe consequences for the natural environment. For example, in 1989 there were 5.3 billion people in the world, or 93 million more than in 1988. At this rate, world population will double in less than forty years. As one result, 100 acres of rain forests are being destroyed every minute. Half of these forests are expected to be gone before the year 2000. Yet at present, 70 percent of Third World families depend solely on wood for their beating/cooking fuel. Other effects include rapid loss of species, which is well-documented, and a correlation with global warming which is still being analyzed. Dominant pattern _____________________.
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【多选题】Which two of the following are true regarding the distance-vector and link-state routing protocols?
A.
Link state sends its complete routing table out all active inteces at periodic time intervals.
B.
Distance vector sends its complete routing table out all active inteces at periodic time intervals.
C.
Link state sends updates containing the state of its own links to all routers in the internetwork.
D.
Distance vector sends updates containing the state of its own links to all routers in the internetwork.
【单选题】What are the advantages of Distance Vector Routing over Link State Routing?
A.
Converges faster, especially when links go down
B.
Requires less computation in each router
C.
The computed routes are of better quality
D.
Requires more information to be exchanged by the routers
【多选题】A、B、C和D都是周期表中前20号元素,已知A的阳离子和C的阴离子具有相同的核外电子排布,且能形成组成为AC的化合物;C和D属同族元素,其中C中核外电子数是D中核内质子数的2倍.B和D同周期且B的同素异形体之一是原子晶体.下列说法中正确的是(  )
A.
D元素处于元素周期表中第2周期第Ⅵ族
B.
AD 2 中可能既有离子键又有共价键
C.
四种元素的原子半径A>C>D>B
D.
BCD分子一定是直线型非极性分子
【单选题】It’s really unwise of some agers from low-income families to spend a large sum of money on Apple products ______ they could buy other cheaper brands.
A.
unless
B.
when
C.
so that
D.
in case
【单选题】如果一个人老是抱怨分配给他的工作,但是没有人理睬他,也不给他换工作,也许过一段时间他就不抱怨了。这体现的是强化理论里面的( )。
A.
惩罚
B.
消除
C.
负强化
D.
正强化
【单选题】X、Y、Z、W都是元素周期表中前20号元素,它们的原子序数依次增大。已知: ① W的阳离子和Z的阴离子具有相同的核外电子排布,且能形成组成为WZ的化合物; ② Z和Y属同族元素,它们能形成两种常见化合物; ③ X和Y属同一周期元素,它们能形成两种气态化合物; ④ W和X能形成组成为WX 2 的化合物; ⑤ X和Z不在同一周期,它们能形成组成为XZ 2 的化合物。 下列说法不正确的是
A.
XY 2 是以极性键结合成的非极性分子
B.
XY 2 、XZ 2 的化学键类型和晶体类型都相同
C.
WY、ZY 2 分子中所有原子最外层都为8电子结构
D.
离子半径大小顺序为Y<W<Z
【多选题】The statements below compare and contrast link state and distance vector routing protocols. Which of these are true?()
A.
Distance vector protocols send the entire routing table to directly connected neighbors.
B.
Distance vector protocols are responsible for sending updates to all networks listed in the routing table.
C.
Link state protocols are responsible for sending the entire routing table to the whole network.
D.
Link state protocols send updates regarding their own links status to all other routers on the network.
【单选题】关于MOSFET的短沟道效应和窄沟道效应描述错误的是()
A.
MOSFET的短沟道效应是指当MOSFET的沟道长度可与源,漏的结深相比拟时,阈值电压随着沟道的缩短而减小
B.
MOSFET的短沟道效应主要是由于栅氧两端的电压降减小,进而引起阈值电压减小
C.
MOSFET的窄沟道效应是指沟道宽度W很小时,阈值电压将随着W的减小而增大
D.
MOSFET的窄沟道效应主要是由于栅氧两端的电压降减小,进而引起阈值电压增大
【多选题】Which two of the following are true regarding the distance-vector and link-state routing protocols?(Choose two.)
A.
Link state sends its complete routing table out all active inteces on periodic time intervals.
B.
Distance vector sends its complete routing table out all active inteces on periodic time intervals.
C.
Link state sends updates containing the state of their own links to all routers in the internetwork.
D.
Distance vector sends updates containing the state of their own links to all routers in the internetwork.
【单选题】A、B、C、D都是周期表中前20号元素,已知A的阳离子和C的阴离子具有相同的核外电子排布,且能形成组成为AC的化合物;C和D属同主族,其中C的核外电子数是D的核内质子数的2倍.B和D是同周期元素且A和B能形成AB 2 型化合物.下列说法中正确的是(  )
A.
D元素处于元素周期表中第二周期Ⅵ族
B.
BC 2 分子一定是极性分子
C.
AB 2 中可能既有离子键又有共价键
D.
四种元素的原子半径大小一定是A>C>D>B
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