adj.清楚的；简单的；坦白的；平常的；朴素的；纯的
n.平原；广阔的区域
adv.完全地；纯粹地
It was plain to everyone that she was not happy. 她并不幸福,这是明摆着的事实。
The restaurant serves plain home-made meals. 那个餐馆供应简单的家常菜。
She was admired for her plain speaking. 她说话坦白,这一点令人钦佩。
Most people see great men as wizards; however, they are just plain people. 大多数人觉得伟人是奇才,然而,他们只不过是平常人。
I drink only pure water after taking exercises. 运动之后我只喝纯净水。
用作名词 (n.)The wind whipped across the plain. 大风扫过平原。
The mountain stands tall and upright on the vast plain. 这座高山屹然矗立在广阔的平原上。
Shanghai in Yangtze Delta alluvial plain, low-lying, the network of waterways covered with vast shoals resources. 上海位于长江口冲积平原，地势低洼，河网密布，拥有广阔的滩涂资源。
用作副词 (adv.)Beck went plain crazy with anger on the day when he received his Dear John from his girlfriend. 贝克收到他女朋友的绝交信的那天简直都气疯了。
That is just plain stupid. 那简直是愚不可及.
plain sailing一词表示“一帆风顺”，源自航海词汇，指采用简便的平面海图的导航。
adj.(形容词)plain作形容词的基本意思是“清晰的,明白的”,指能被人清楚地看到或听到。plain作“朴素的,简单的,平常的”解时,可指衣着朴素,缺乏装饰; 也可指人的相貌平常,没有特别引人注目之处。plain作“坦白的,坦率的,真诚的”解时,一般指人的行为和思想。plain作以上解释时在句中可用作定语或表语。
plain还可作“完全的,十足的,彻底的”解,在句中只用作定语,无比较级和最高级形式。
当plain的主语是动词不定式或that从句时,常用于形式主语结构。
n.(名词)plain用作名词意思是“平原”,指起伏极小,海拔较低的广大平地,常用作复数形式。
