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It is a beautiful day here and I am sitting under the big tree at the e of the小题1: garden. I have just returned from a long bike ride to an old castle. seems 小题2: amazing that at my age I am still (健康) enough to cycle 20 kilometers in 小题3: An afternoon. It’s my b in two weeks’ time and I’ll be 82 years old! I think小题4: my long and active life must be to(由于) the healthy life I live. 小题5: This brings me to the real (原因) for my letter, my dear grandson. 小题6: Your mother tells me that you started s some time ago and now you find 小题7: it difficult to give it . Believe me, I know how easy it is to begin smoking 小题8: and how tough to s . You see, during adolecence 小题9: I a smoked and became addicted to cigarettes. 小题10:
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【简答题】求解下列线性规划问题： (1)max z=x 1 +2x 2 , s．t．2x 1 +x 2 ≤8， -x 1 +x 2 ≤4， x 1 -x 2 ≤0， 0≤x 1 ≤3，x 2 ≥0； (2)min f=-3x 1 -11x 2 -9x 3 +x 4 +29x 5 ， s．t．x 2 +x 3 +x 4 -2x 5 ≤4， x 1 -x 2 +x 3 +2x 4 +x 5 ≥0， x 1 +x...
【单选题】排水管渠的最小设计流速,应符合下列规定:污水管道在设计充满度下为___;雨水管道和合流管道在满流时为___;明渠为___。
A.
0.6 m/s、0.75 m/s、0.4 m/s
B.
0.75 m/s、0.75 m/s、0.4 m/s
C.
0.75m/s、0.6 m/s、0.4 m/s
D.
0.6 m/s、0.6 m/s、0.4 m/s
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