解:第一步,从三位穿西装的数学家中选出两位,将这两位排列为一个整体,有A_3^2=3×2=6(种);第二步,将4位未穿西装的数学家进行排列,有A_4^4=4×3×2×1=24(种);第三步,这个整体与另外一位穿西装的数学家插入到4位未穿西装的数学家所形成的5个空位中,有A_5^2=5×4=20(种)。综上所述,共...
People plant a great number of young trees in the mountains.When the trees grow big and tall enough, they are cut down by workers and carried out of the mountains to the paper mill where fine paper is made from wood.Then it is taken to every corner of the country and used for differe...
Warm and cool air move from place to place and that makes winds.When the wind changes speed, it often brings a change in the weather. For example, when the air moves at a low speed, it makes a breeze, but when the air moves very fast, it makes big winds. The direction of the ...
Looking at Huang Baijie again, he was earnestly searching for and picking it up, and the sweat on his face didnt even have time to wipe it off; What makes me laugh the most is Tang Yunong, who used his little hands to pick up garbage to wipe sweat off his face, but actually wiped ...
A machine that makes the photographic copies of documents. Tidy. Arranged neatly and with everything in order. Fax machine. Feel bored. Be in order. The following short dialogs contain expressions often used by new employers. When they forced to come to the company. Listen and answer the ...
Climate change can change the wind direction. What may happen to the migratory birds? A. They will change their migratory routes. B. They will stop migrating. C. They will migrate more frequently. D. They will migrate in groups. 相关知识点: ...
D.Itmakesitalmostimpossibletofindthetruecauseofmemoryloss. E.Thisruleappliestothebrainaswell. F.Itisveryhelpfultohavearegularplacetoputthingsin. G.Thefollowingarethetopthreereasonsformemorylossandhowyoucanavoidthem. 1. 2. 3. 4. 5. 高中英语 选择性必修 第二册 第53页 53 分钟能力强化组合练(十四)...
A.The prevailing wind for the area.B.The combing of the extremities of exposed trees.C.The behavior of celestial objects.D.The way of the growth of trees. 相关知识点: 试题来源: 解析 B 正确答案:B解析:细节推断题。第三个小标题指出,我们可以利用风向来指导旅行,每个地方都有一到两种主要的风向...
Suffering Wrong Kind of Rainfall; House Doctor Peter Fall Looks at What Happens When the Wind Changes Direction
2.They had a change of heart .(片中) change of heart 改变态度,改变想法,改变主意例:I was going to break up with my girlfriend but had a change of heart and decided not to. 3.The chiefs give me the go ahead (片中) go ahead 得到许可(这里用作n)例:I just got the go ahead from...