41. The Astronauts Memorial Foundation honours all American astronauts _________ have lost their lives on missions or in training. A. whom B. x C. which D. who 42. He's so brilliant and he can do anything _________. A. Out of this world B. The sky's the limit C. It's over the moon D. Once in a blue 43. I _________ down to earth on my first Monday back to school after my holiday in NhaTrang. A. come over B. come back C. come in D. come on 44. Yuri Gagarin made the first space flight _________ success attracted worldwide attention. A. which B. when C. whose D. where 45. Aircraft flying in _________ arcs create microgravity for tests and simulations that last 20-25 seconds. A. straight B. oval C. circular D. parabolic 46. The launch of the Space Shuttle Endeavour _________ broadcast live this morning. A. has been B. was being C. was D. had been 47. Dan: "Do you like to drink tea?" Ben: "I love coffee, but I only drink tea _________in a blue moon." A.one B. once C. first D. only 48. To walk on the moon, the astronauts had to carry a suitcase _________ contained oxygen. A. which B. it C. having D. where 49. Yuri Gagarin became the first person to eat and drink in _________. A. weight B. gravity C. specific gravity D. microgravity 50. I passed all my exams - I'm _________! A. out of this world B. the sky's the limitC. over the moon D. once in a blue moon