烧锅炉的时候，用铲子送煤，铲子往往并不进入灶内，而是停在灶前，煤就顺着铲子运动的方向进入灶内，为什么？

答：用铲子送煤时，当铲子突然在灶前停止运动，煤由于____ 要保持原来的____ 状态，继续沿着____ 的方向进入灶内．

    What do you know about the sea? Some people have seen it, but others haven't. The sea looks beautiful on a fine sunny day and it can be very rough when there is a strong wind. What other things do we know about it?

    Of course, the sea is very large. In the world there is more sea than land. If you swim in the sea, you know that the water is salty. Rivers take salt from the land into the sea. Some places of the sea are more salty than other places. Do you know the Dead Sea? Fish can't live in it!

我国在坚持不结盟原则的前提下广交朋友。截至2014年底，我国同67个国家、5各地区和地域组织建立了不同形式、不同程度的伙伴关系，基本覆盖了世界上主要国家和重要地区。“结伴但不结盟”的外交实践表明我国（   ）　　

①尊重各国人民选择的发展道路与价值观念

②通过伙伴关系应对全球性挑战和第三方威胁

③处理国际问题时主要根据伙伴国的利益制定政策

④在和平共处五项原则基础上全面发展同各国的友好合作

下列有关燃烧的说法正确的是                （        ）