youdao

We'll need a flat surface to play the game on.

我们得有个平面才能玩这个游戏。

《牛津词典》

The common aim of all such systems is to represent an ellipsoidal shape on a flat surface — distortion in some places is almost inevitable.

这些系统的共同目标是在平面上表示椭圆形状 — 有些地方失真也是不可避免的。

youdao

It is a small device that you move around on a flat surface in front of a computer.

VOA: special.2010.08.01

"Well,one of the things that's interesting about these flexible sheets is that they can be curved, so you could imagine putting them in unconventional forms, like on the surface of a vehicle or something like that, where you don't have a flat surface."

VOA: standard.2010.02.19

They can develop as flat, discolored areas of skin or as raised growths, often with a rough surface.

VOA: special.2010.07.06

What if all you needed to tap, swipe and type on was a flat surface and projected light?

FORBES: Meet The Projector That Could Put The iPhone's Screen On Your Desk

Before, 50-year-old Trevor Prideaux had to balance the phone on his arm or put it on a flat surface.

FORBES: Man Installs Nokia Phone In His Prosthetic Arm

Racing helmets must guard riders against a 14-mph crash onto a flat surface, or a fall from approximately six feet.

WSJ: Cycling's Occupational Hazard