请教几个英语方面的小问题：1、on earth与on the earth 区别 2、you are helpful 与 you have been helpf

题目

请教几个英语方面的小问题：1、on earth与on the earth 区别 2、you are helpful 与 you have been helpf
2、you are helpful 与 you have been helpful 区别
3、ride a bicycle 与ride bicycle 区别
4、in her hair 与 on her hair 区别

答案

1.on earth / on the earth / the Eearth
on earth 作为固定搭配,意思是:在世界上,
on the earth ,earth 不大写时,earth 与ground 类似,此时on the earth 相当与on the ground
on the Eearth,Eearth 大写,前有the ,on the Eearth ,就是on + 地球; 换句话说,如果想用earth 表示地球时候,earth 应该大写首字母,前加the,是正规的用法.
2.your are helpful/ you have been helpful
you have been helpful,完成时态,表明你做了一些贡献,对人有过帮助.
you are helpful,看不出你是否正在提供帮助或者已经提供了帮助,相当于你是有用处的.
3.ride a bicycle/ ride bicycle
ride a bicycle,bicycle 可数名词,前面用a 是正常的
ride bicycle,bicycle 可数名词,前面没有a,the,this,one's 等修饰成分,也没用复数形式,是错误的.
4.in her hair/ on her hair
区别就应该是in /on 之间的区别,in 在内部,on 在表面