Cho lăng trụ ABC.A'B'C' có các mặt bên đều là hình vuông cạnh a. Khoảng cách giữa hai đường thẳng A′B và B'C là? Tương tự đoạn vuông góc chung của A'B' và BC' trong lăng trụ ABC.A'B'C' có đáy là tam giác đều. AA' vuông góc với (ABC) là ?

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1. Don’t _______ him on to join a gang: nothing could be worse for him! A. egg B. toast C. butter D. knife 2. Many companies seem to reach the _______ of disaster before anybody has tried to get something done. A. side B. precipice C. edge D. brink 3. I am not surprised that your brother is angry; you spent half an hour _______ him up about an issue he cares about deeply. A. spinning B. turning C. winding D. twirling 4. Although Gail thought she should have won first place, she _______ her pride and congratulated her rival. A. exerted B. swallowed C. bore D. aroused 5. I had spent two months worrying about it and I was glad to get it off my _______. A. shoulders B. head C. chest D. mouth 6. That he was using unscrupulous research methods only came out because his assistant _______ on him to the press. A. ratted B. hounded C. fished D. bugged 7. The phrase ‘money doesn't buy happiness’ is a cautionary cliché that keeps us from blindly lining your pockets with _______ in the hope that we’ll feel happier. A. stash B. hoard C. stock D. dosh 8. If there happened to be both rich and poor people, as there happen to be both black and white ones, then the advantages of the _______ might well spread in time to the hard-up. A. well-heeled B. big-hearted C. open-handed D. tight-fisted 9. The government has agreed to _______ an additional £5 million to schools in underprivileged regions. A. dole out B. tip off C. crack down D. toss off 10. As much as the candidate tried to convince people of his honesty, he could not shake off his _______ past. A. serene B. tranquil C. shady D. frigid Thế này thôi ạ. Em cám ơn trước :3

1. Discussions on the issue of expansion of the company have been in _______ since the outbreak of the disease in the area. A. hitch B. limbo C. feud D. core 2. Viewers were _______ at the incredible sight of the lunar landscape, unable to take their eyes off the screen until the very end of the broadcast. A. switched B. devised C. transfixed D. stifled 3. Having lost her mother at an early age, Mary felt she had become a mere _______, having to do absolutely everything for her five brothers and sisters. A. taskmaster B. workmate C. slavedriver D. workhorse 4. Keith’s _______ income looks impressive, but once tax and social security contributions are deducted, it’s not so much. A. full B. grand C. net D. gross 5. We have developed rapid order processing to _______ deliveries to customers. A. expedite B. fasten C. heighten D. quicken 6. The operation was a success, but the patient died of _______. A. complications B. symptoms C. after-effects D. ramifications 7. Increasing terrorism in the region puts a new _______ on the situation. A. complexion B. disposition C. outlet D. tantrum 8. If you need help, please don’t hesitate to call me. I can be there _______. A. in a fix B. in a flash C. in a daze D. in the bag 9. He felt his heart _______ as his bride-to-be began her walk down the aisle. A. fasten B. quicken C. expedite D. heighten 10. My car broke down and I had to _______ a huge sum of money to have it towed and serviced. A. splash out B. fork out C. put aside D. pay off Mọi người ggiair thích cho em nữa ạ