在远距离输电中,如果输送功率和输送距离不变,要减少输送导线上热损耗,目前最有效而又可行的输送方法是    （      ）

蹦床运动是一种深受青年人喜爱的运动，当运动员从蹦床上弹起后在空中向上运动的过程中，其动能和重力势能的变化是

植物必需的有机物是通过____ 合成的，光合作用实现了两个转化：一是将无机物转化为____ ，二是将光能转化为____ 。

    Hello, everyone!____is a photo of my cousin. Tom's ____ in the photo. Tom is on the left side (一侧) and his ____is on the right side. Who's this man? He's Toms father. He's very ____. Tom has a dog, and the dog's ____is Lucky. It is brown. Tom likes his dog very much.