消费是整个经济链条的最后一个环节,在经济学的意义上,投资每增长一个百分点,能拉动经济增长0.2%,而消费每增长一个百分点,能拉动经济增长0.8%,是投资的4倍。下列措施中,有助于促进居民消费的是(　　)

①提高银行存款利率

②进一步完善社会保障体系

③努力增加城乡居民收入

④适当拉大居民收入差距

如图，实验室一台手摇交流发电机，内阻r=1.0Ω，外接R=9.0Ω的电阻．闭合开关S，当发电机转子以某一转速匀速转动时，产生的电动势e=10 $\sqrt{2}$ sin 10πt（V），则（   ）

完形填空。 
   Hi! I am a Chinese boy. I'm from Shanghai. 1 name is Li Qiang. I’m thirteen years old. I'm in Yucai Middle School in Shanghai. I 2 a round face, a big nose, a small mouth 3 eyes. Michael is a new student 4 our school. He 5 the U.S.A. He is tall and he 6short black hair. He 7 cool. He is thirteen years old, too. He and 8 are in the same school but in different 9. My English is not good, and he often10 me. We are good friends now.

计算它每分钟能奔跑____千米．(得数保留两位小数．)

34.5千米/小时