a. 地球的, 俗世的, 可能的

earth/earthquake/quake/earthworm/earthly/soil/mud/muddy/clay/globe/global
记忆：
1. earth [ E:W ] n. 地球（the earth）, 陆地, 泥土, 尘世 We have only one earth. To destroy the earth means to destroy ourselves.我们只有一个地球。毁掉地球就是毁掉我们自己。
2. earthquake [ 5E:Wkweik ] n. 地震 When can we predict earthquakes instead of reporting them?我们什么时候能预测地震而不是报道地震？
3. quake [ kweik ] v. & n. 震动；颤抖震动或发抖 The building was quaking terribly at that time.那时大楼震动得很厉害。
4. earthworm [5\:Ww\:m] worm, n.虫, 蠕虫 earthworm, n. 蚯蚓 The earthworm is good for our crops.蚯蚓对我们的庄稼有好处。
5. earthy [ 5E:Wi ] adj. 土的, 粗陋的, 朴实的 The houses in the village are mostly earthy.村里的房子多数是用泥土打造的。
6. earthly [ 5E:Wli ] adj. 现世的, 地球的, 俗世的 We live an earthly life. That is to say, we can’t avoid earthly matters.我们要过世俗的生活，也就是说，我们不能回避世俗的东西。
7. soil [ sCil ] n. 土壤, 土地 The seed must be covered with soil.种子必须用土壤盖住。
8. mud [ mQd ] n. 泥, 泥浆, 泥泞 Multi-User Dungeons的简写, 多用户网络游戏 Many young people go to net bars to play MUD.很多年轻人到网吧去现网络游戏。
9. muddy [ 5mQdi] adj. 泥泞的 The road is still muddy. 道路上仍是一片泥泞。
10. clay [ klei ] n. 粘土, 泥土 The Buddhist figures are mostly made of clay.这些佛像多数是用粘土做的。
11. globe [ ^lEub] n. 球体, 地球仪, 地球 The teacher brought a globe to explain the change of global climates.老师带了一个地球仪来讲解全球气候的变化。
12. global [ 5^lEubEl] adj. 球形的, 全球的, 全世界的 Any so-called global strategy is based on the country’s own interest.任何所谓的全球战略都是以其国家利益为基础的。
另类阅读：
How on earth does an earthquake affect the soil/earth on the earth/globe? Let me show you with this globe.