如图所示，一质量M=40kg、长L=2.5m的平板车静止在光滑的水平地面上．一质量m=10kg可视为质点的滑块，以v₀=5m/s的初速度从左端滑上平板车，滑块与平板车间的动摩擦因数μ=0.4，取g=10m/s²．

用滑轮组提起重物，下列做法中能提高机械效率的是（不考虑绳重及摩擦）（　　）

    I have a good friend in my class. His name is Jim. He is from England. He is in China with his parents. He likes China. He likes Chinese food very much. He has breakfast at home. He eats an egg. bread and milk for breakfast. He doesn't like fish. He has lunch at home. The lunch in his school is delicious. He can have different kinds of food for lunch. He eats rice, meat and vegetables. Sometimes he has noodles and dumplings. He has supper at home with his friends. Sometimes he goes out to eat with his friends. He has meat , vegetables and fruit for dinner.

就业区位商(LQ)用来衡量产业集群状况。其公式为： 。其中，Eij指区域j里面产业i的就业人数，Ej指j区域的总就业人数，Ein指整个国家i产业的就业人数，而En是指国家的总就业人数。读下图“2012年电子信息产业省际就业区位商示意图”，与其他省（区、市）相比，该省（区、市）吸引电子信息产业集聚的独特优势是(    )