根据首字母提示或括号内的汉语意思拼写单词。

1. They marked the _____ (边界) of the football fields.

2. The still water r_____ the full moon.

3. Our ship grounded in s_____ water.

4. The air by the sea is _____ (清新的) and healthy.

5. The machines were arranged in _____ (整齐的) rows.

6. That woman has a very s_____ tongue.

7. They climbed the s_____ mountain inch by inch.

人类目前所消耗的能量主要来自于化石燃料．石油炼制的产品中，可用作汽车燃料的是______．由于能源消耗的急剧增加，大气中二氧化碳含量不断上升，加剧了______，降低空气中二氧化碳含量的研究有两个方向：一个是______，另一个是______．符合“低碳”环保理念的一种能源是______．