fly的复数形式为是变y为i再加es，即flies。fly可作名词、动词和形容词，作为名词时，意为苍蝇、前裆开口；作为动词时，意为飞翔、航行、飞行；作为形容词时，意为机灵的、不会上当的、漂亮的。
fly的中文释义及用法介绍1、作为动词时，意思有飞;飞翔;(在空中或宇宙)飞行，航行;(乘飞行器或航天器)航行，飞行。
例句：A wasp had flown in through the window.
一只黄蜂从窗口飞了进来。
They were on a plane flying from London to New York.
他们在从伦敦飞往纽约的飞机上。
Is this the first time that you've flown?
这是你第一次乘飞机吗？
He's learning to fly.
他在学习驾驶飞机。
The stranded tourists were finally flown home.
受困的游客终于由飞机送返家园。
Rumours had been flying around the workrooms all morning...
整个早上流言在各工作间传来传去。
2、作为名词时，意思有蝇;苍蝇;(作钓饵的)苍蝇，假蝇;(裤子的)前裆开口。
例句：A fly was buzzing against the window.
一只苍蝇嗡嗡地飞着，直撞窗子。
Your fly is undone!
你的裤子前裆没拉上！
3、作为形容词时，意思有机灵的;机警的;不会上当的;时髦迷人的;漂亮的。
例句：What I'd give to be a fly on the wall when Davis finds out what's happened to his precious cargo.
我多么希望能够看到戴维斯发现他珍贵的货物出事时的样子啊。