He's a snake in the grass. While pretending to be your friend he was slandering you behind your back.

他是个暗敌，表面上装作是你的朋友，背地里却在诽谤你。

《新英汉大辞典》

The Automower does not collect grass, but chops it up finely and leaves it behind as a mulch.

这款自动割草机不能收集割下的草，但是它能够将草割得很细，留下来用做护根肥料。

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Behind the window was a meadow with tall, lush grass, and wildflowers.

在窗户后面是一片拥有又高又茂盛的青草和野花的草地。

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All things appeared headed toward the no-hitter after Matt Carpenter made a sliding stab of a grounder about 10 feet onto the outfield grass behind second base for the first out in the eighth.

NPR: Cardinals Beat Rockies 3-0 On Wainwright Gem

While not going at full speed, Jeter looked smooth going three times from first to third and three times from third to first on the grass just behind the infield dirt.

WSJ: Jeter resumes on-field hitting

Pineda, who missed all of last season after right shoulder surgery, parked his SUV Wednesday in a grass parking lot behind the left-field fence at the Yankees' minor league complex.

WSJ: Pineda's SUV window broken by homer