But nobody saw a frog at all.

但是还是没有人看到有青蛙。

youdao

She looked around and saw a frog. He was stretching his thick ugly head out of the water.

她四处看了一下，看到了一只青蛙，它那肥厚而又丑陋的脑袋正伸出水面。

youdao

A mottled snake was sheltering from the heat among the roots of an old tree when he saw a frog coming.

一条花蛇正在一棵老树根下乘凉，看见对面来了一只青蛙。花蛇笑着说：“啊哈！”

youdao

In the late 1800s English physiologist John Langley discovered the muscular nicotinic receptor when he tied a frog muscle to a round drum, put nicotine on the muscle and saw it contract.

FORBES: The Nicotine Cure