题目

在下列关于直线l、m与平面α、β的命题中,真命题是(    )A.若lβ且α⊥β,则l⊥α                 B.若l⊥β且α∥β,则l⊥αC.若l⊥β且α⊥β,则l∥α                  D.若α∩β=m且l∥m,则l∥α 答案：解析:若lβ且α⊥β,则l⊥α或l∥α或lα.若l⊥β且α⊥β,则l∥α或lα.若α∩β=m且l∥m,则l∥α或lα.故只有B可由定理推出. 答案:BI have come to believe that a great teacher is a great artist and that there are as few as there are any other great   41  . It might even be the greatest of the art   42   it’s the medium between the human mind and spirit.I shall speak only of my first 43 because in addition to the other things, she 44  discovery.She aroused us to shouting, book waving discussions. She had the   45   class in school and she didn’t even seem to know it. We could   46   stick to the textbooks. She   47   curiosity into us so that we found facts or truths   48   in our hands like captured fireflies.She was fired and perhaps 49 so, for failing to teach fundamentals. Such things must be   50 . But she left us a passion for the pure  51  world and she filled me with a 52 which has never left. I could not do simple math but   53   her I sensed that mathematics was very much like music.When she was fired,  54   came over us but the light did not   55  . She left her signature for us, the literature of the teacher who wrote on our   56  . I suppose that to a larger extent I am the   57   manuscript(手稿) of the high school teacher. What deathless power   58   the hands of such a person.I can tell my son who looks forward with   59   to fifteen years of unpleasant study that somewhere in the dusty dark a magic   60   happen that will light up the years … if he is very lucky.41．A．artistsB．scientistsC．doctorsD．actors42．A．whenB．sinceC．howeverD．so43．A．friendB．classmateC．teacherD．roommate44．A．madeB．foundC．createdD．brought45．A．quietestB．noisiestC．loudestD．bravest46．A．neverB．alwaysC．oftenD．forever47．A．frightenedB．forcedC．breathedD．preferred48．A．remainedB．leftC．laidD．hidden49．A．rightlyB．wronglyC．doubtfullyD．sadly50．A．practicedB．learnedC．researchedD．experimented51．A．familiarB．mysteriousC．knowableD．frightful52．A．courageB．determinationC．pleasureD．curiosity53．A．throughB．withC．toD．before54．A．gladnessB．surpriseC．sadnessD．hesitation55．A．put offB．make upC．take awayD．go out 56．A．mindsB．namesC．papersD．books57．A．correctedB．copiedC．unsignedD．rewritten58．A．deals withB．lies inC．adds upD．grows up59．A．horrorB．excitementC．disappointmentD．joy60．A．mayB．shouldC．mustD．can’t