The total resistance of a parallel circuit is always （）.

A . directly as its length and inversely as its cross-sectional area B . inversely as its length and directly as its cross-sectional area C . directly as its length and directly as its cross-sectional area D . inversely as its length and inversely as its cross-sectional area

A . increases by the square of the original value B . increases C . remains the same D . decrease

A . Power factor B . Power ratio C . compression ratio D . Compression factor

A . hogging stresses B . sagging stresses C . racking stresses D . shearing stresse

A . cylinder liner B . coupling flange C . cylinder cover D . piston crow

A . The voltage drop across each resistor is the same B . The total current flow equals the reciprocal of the sum of the individual currents C . The total resistance equals the sum of the individual resistances D . The total voltage equals the sum of the individual voltages across each resistance

A . the packetization size B . the serialization of the interface C . the quantization D . the packet rate E . the UDP overhead F . the TCP overhead

A . one-third B . two-thirds C . one-fourth D . two-fourth

A . seawater contamination B . frequent surface blows C . dissolved oxygen deaeration D . frequent bottom blow

A . does not exceed B . should exceed C . should be up to D . should be no more tha

A . Globe valve B . Butterfly valve C . Gate valve D . Packless valve

A . reduce B . rise C . raise D . fall

A . larger B . equal C . smaller D . equivalent

A．Y B．N C．NG

A.one B.less than one C.more than one D.negative one

A . return on investment (ROI) B . net present value (NPV) C . discounted cash flow (DCF) D . B and C E . All of the above.

A.vertical moments B.transverse position of the center of gravity C.inclining moments D.righting moments

The ocean bottom (a region nearly 2.5 times greater than the total land area of the Earth) is a vast frontier that even today is largely unexplored and uncharted. Until about a century ago, the deep-ocean floor was completely inaccessible, hidden beneath waters averaging over 36,000 meters deep. Totally without light and subjected to intense pressures hundreds of times greater than at the Earth's surface, the deep-ocean bottom is a hostile environment to humans, in some ways as forbid- ding and remote as the void of outer space. Although researchers have taken samples of deep-ocean rocks and sediments for over a century, the first detailed global investigation of the ocean bottom did not actually start until 1968, with the beginning of the National Science Foundation's Deep Sea Drilling Project (DSDP). Using techniques first developed for the offshore oil and gas industry, the DSDP's drill ship, the Glomar Challenger, was able to maintain a steady position on the ocean's surface and drill in very deep waters, extracting samples of sediments and rocks from the ocean floor. The Glomar Challenger completed 96 voyages in a 15-year research program that ended in November 1983, During this time, the vessel logged 600,000 kilometers and took almost 20,000 core samples of seabed sediments and rocks at 624 drilling sites around the world. The Glomar Challenger's core samples have allowed geologists to reconstruct what the planet looked like hundreds of millions of years ago and to calculate what it will probably look like millions of years in the future. Today, largely on the strength of evidence gathered during the Glomar Challenger's voyages, nearly all earth scientists agree on the theories of plate tectonics and continental drift that explain many of the geological processes that shape the Earth. The cores of sediment drilled by the Glomar Challenger have also yielded information critical to understand the world's past climates. Deep-ocean sediments provide a climatic record tracing back hundreds of millions of years, because they are largely isolated from the mechanical erosion and the intense chemical and biological activies that rapidly destroy much land-based evidence of past climates. This record has already provided insights into the patterns and causes of past climatic change information that may be used to predict future climates. The author compare the ocean bottom to a "frontier" in paragraph 1 because it______. A．is a quite promising place. B．is out of the understanding of many scientists. C．attracts courageous explorers. D．is an unknown research area to the scientists.

A.larger than the greatest branch resistance B.smaller than the lowest branch resistance C.equal to the sum of the individual branch resistances D.one-half the sum of the individual branch resistances

A．A＄0balance B．A＄4,300debitbalance C．A＄4,300creditbalance D．A＄5,700debitbalanc E．A＄5,700creditbalanc E．

是 否