watermelon
例句：（1）西瓜内红外绿。
A watermelon is red inside and green outside.
（2）现在是伏天，西瓜正当令。
These are the dog days; watermelons are just in season.
（3）这西瓜好甜哪！
This watermelon is really sweet!
（4）都快冬天了，西瓜早就下市了。
It is almost winter and watermelons have long gone out of season.
西瓜[xī guā]
[watermelon] 一种一年生蔓生藤本植物,开淡黄色的花,叶有5-7个深裂片,为热带非洲原产,现已广泛栽培
参考资料
吴光华.汉英大词典.上海：上海译文出版社，2010