A：
B：
We live on the Earth．The Earth was ____ ，but now some parts are dirty．Let's work together to keep the Earth pretty and healthy because the Earth is only home for all the living things．We should ____．We should ____．We also need water and trees．So we shouldn't ____．We should stop ____．
在日常生活中，用100N的拉力无法提起重150N的物体的简单机械是 （ ）
明清时期，民间流传着“湖广熟，天下足”的谚语，这里的“湖广”主要指的是今天的（ ）
