An English gent leman always takes an umbrella and wears a hat. Why? In England, it rains often. The rain comes at any time, so an umbrella is necessary (必要的) in people's life. English gentlemen love to take a long black umbrella. It is useful when the rain comes. And it is also a style. The hat plays an important part in their life too. If two men meet in the street,  they take off (脱掉)  their hats to show their respect (尊重) to each other. If a man visits his friend, he takes off his hat frst when he gets into the room. If he goes to a party, he can only put the hat on his chair, but not on the table. You don't have the two things, but you can still (仍然) be a gentleman. Always be nice to others and be ready to help others. Show your respect and love to old people, women and children. Never shout. Never lose your temper (发脾气).

（Ⅰ）若a，b，c成等差数列，证明：sinA+sinC=2sin（A+C）；

（Ⅱ）若a，b，c成等比数列，且c=2a，求cosB的值．

法国是欧洲西部最大的粮食生产国和世界最大的葡萄酒产地，如图是法国农产品分布图，读图完成以下问题。

如图，△DEF是由△ABC通过平移得到，且点B，E，C，F在同一条直线上．若BF=14，EC=6．则BE的长度是（　　）