要从代号为A、B、C、D、E、F的六个侦察员中挑选出若干人去破案,人选的配备要求,必须注意下列各点: ①A、B两人至少去一个人 ②A、D不能一起去 ③A、E、F三人中要派两人去 ④B、C两人中去一人 ⑤C、D两人中去一人 ⑥若D不去,则E也不去;由此可见:
A. 挑了A、B、C、F四人去
B. 挑了A、B、F三人去
C. 挑了B、C、D、E四人去
D. 挑了B、C、E三人去
Space enthusiasts look to the day when ordinary people, as well as professional astronauts and members of Congress, can leave Earth behind and head for a space station resort, or maybe a base on the moon or Mars. The Space Transportation Association, an industry lobbying group, recently created a division devoted to promoting space tourism, which it sees as a viable way to spur economic development beyond Earth. The great stumbling block in this road to stars, however, is the sheer difficulty of getting anywhere in space. Merely achieving orbit is an expensive and risky proposition. Current space propulsion technologies make it a stretch to send probes to distant destinations within the solar system. Spacecraft have to follow multi-laver, indirect trajectories that loop around several planes in order to gain velocity from gravity assists. Then the craft lack the energy to come back. Sending spacecraft to other solar systems would take many centuries. Fortunately, engineers have no shortage of inventive plans for new propulsion systems that might someday expand human presence, literally or figuratively, beyond this planet. Some are radical refinements of current rockets or jet technologies. Others harness nuclear energies or would ride on powerful laser beams. Even the equivalents of "space elevators" for hoisting cargoes into orbit are on the drawing board. "Reach low orbit and you are halfway to anywhere in the Solar System," science-fiction author Robert A. Heinlein memorably wrote, and virtually all analysts agree that inexpensive access to low Earth orbit is a vital first step, because most scenarios for expanding humankind’ s reach depend on the orbital assembly of massive spacecraft or other equipment, involving multiple hunches. The need for better launch systems is already immediate, driven by private and public sector demand. Most commercial payloads are destined either for the now crowed geo-stationary orbit, where satellites jostle for elbow room 36,000 kilometers above the equator, or for low-Earth or bit, just a few hundred kilometers up. Low-Earth orbit is rapidly becoming a space enterprise zone, because satellites that close can transmit signals to desktop or even handheld receivers. Scientific payloads are also taking off in a big way. More than 50 major observatories and explorations to other solar systems’ bodies will lift off within the next decade. The pressing demand for launches has even prompted Boeing’s commercial space division to team up with RSC—Energia in Moscow and Kvaerner Maritime in Oslo to refurbish an oil rig and create a 34,000—ton displacement semi-submersible launch platform that will be towed to orbitally favorable launch sites. Which of the following statement can NOT be inferred from the passage
A. When traveling in space, spacecraft take indirect route to avoid gravity from the other planets.
B. Space engineers are now developing space elevators.
C. It will take the current spacecraft several hundred years to travel to other solar systems.
D. Scientists from different countries are working together to develop new space technologies.
中国申请新西兰学生签证的数据统计(截止2000年3月10日) 1999.10.01-2000.03.10 1998.11.01-1999.09.30 1998.07.01-1998.09.10 1997.09.30-1998.07.01 接收的申请人总数 2277人 6011人 1382人 306人 原则获得签证或已 经获得签证的人数 1243人 2865人 449人 180人 拒签的人数 394人 3128人 933人 126人 获得签证及签的 申请合计 1637人 5993人 1382人 306人 从1997.09.30到2000.03.10间,接收的申请人总数为:
A. 8955
B. 9878
C. 9976
D. 9650