将小球以3m/s的速度水平抛出，它落地速度为5m/s，小球在空中的运动时间为（g

Transportation Decision Transportation decision consists of the following parts: 1.Selection of the mode is determined by the consideration of distance,cargo weights,linkage,timing and other requirements.Generally speaking,rail has high fixed cost and the relatively low variable cost.It can move heavy,large quantity of cargo in the long distance.But,rail is disadvantaged because of the longer transit time and less frequent service than motor. Motor carriers such as truck companies offer door-to-door service,that is,the cargo can be shipped from the shipper＇swarehouse to the consignee＇s.Trucking fixed cost is the lowest of any carrier,because the equipment is fairly cheap and the motor carriers do not have to invest in the roads on which they run their operations.However,their variable costs are very high.Its expenses include two major components:firstly,the pick-up and delivery costs;secondly,there are gas or fuel costs,labor expenses and toll roads fees to be paid to highway and toll road operators Therefore,motor transport is good for cargo with small quantity to be shipped within short distances. Water is the predominant choice of transportation as it has the capacity to take greatest quantity,travel longest distance with lowest cost.Transport by sea accounts for 80% of in-ternational trade.The major expenses for water are expenses associated with investment and maintenance of the ships and terminals.For example,a 100000-ton container ship costs US$ 200 million.Terminal associated costs include harbor fees and the cost for loading and unloading the goods. Transport by air has the highest cost but it is fast with the lowest ratio of loss and dam-age.If you need to deliver an urgent order,there is little choice but by air. 2.Transport service provider is selected for its experiences,equipment,services and prices.Competitive in the transport industry usually drives the prices down and motivates for better services.A company also chooses its transport service provider because of its long-standing business relationship with certain shipping companies. 3.The alternative routing and scheduling is specific for motor only because railway and water have strict route and timetable.Motor has special advantage in terms of flexibility.It has the ability to load goods at greater frequency,travel through different routes and making deliveries to different loca-tions.Questions:

How is the transportation mode selected？（）

A.By suppliers.

B.By customers.

C.By consideration of distance,weight,linkage and other requirements.

D.By government requirements.

下列哪些是DOS外部命令？（）

A.Dir

B.Xcopy

C.format

D.edit

一个数（0除外）的1.1倍一定大于这个数．______．（判断对错）

分析广西发展有色金属工业基地的优势区位条件。