⑴This is a photo of Hainan. ____
⑵I got to school by car yesterday.____
⑶Beijing is in the north of China.____
⑷The mountains are really beautiful.____
⑸I went to England last year.____
矮化是作物育种上最有价值的性状之一,它能使作物具有较强的抗倒伏能力和较高的光能利用率,矮秆品种能通过塑造理想株型和合理密植,实现单产的突破.科研人员在玉米田中发现三株矮化植株,对矮化的原因做了如下研究.
下列小数可用科学记数法表示为8.02×10﹣5的是( )
若ai,bi∈R+i=1,2,3,...,n ,求证a1b1+···+anbna1b1+···+anbn≥a1+···+an2 .