Uphill running forces you to drive your arms harder than you do when running on flat ground, so you'll improve your upper body strength.

使您的上身有劲：跑坡道迫使您摆臂比跑平地时更加用力，因此，您的上身力量可以提高。

youdao

Hills. If you run or bike or walk for cardio, you'll want to incorporate hills (after the first month or two of doing it at an easy pace on flat ground).

如果你通过跑步，骑车或者走路来锻炼心脏，那么结合斜坡，效果更好(通常在平地上锻炼一两个月以后进行。)

youdao

This is, of course, assuming they don't suffocate, say, if you dropped them from 40,000 feet, and that they land on relatively flat ground (nothing pointy or the like).

当然，前提是它们不会因窒息而死，(如果你从40000英尺让猫们掉下来它们会因缺氧被憋死)另外一个前提是：它们着陆的地面要相对平坦。

youdao

People driving during a tornado are told to find low ground and lay flat,facedown, with their hands covering their head.

VOA: special.2011.04.19

It sits flat on the ground with the bottom open to the earth.

VOA: special.2010.07.13

Men lay flat on the ground. They prayed for the shelling to stop.

VOA: special.2009.11.05

He resumed throwing Feb. 25 from flat ground and completed a long toss session from 130 feet on Thursday.

WSJ: Harvey nearly perfect for 4 1-3, Mets beat Marlins

The trip through the cities of Illinois, the flat ground of Indiana, and the northern part of Ohio was uneventful.

FORBES: The Night My Wife Became an American

We didn't clock our speeds, but the bike can supposedly top about 15 miles per hour on flat ground with the pedal-assist on, and that sounds about right to us.

ENGADGET: Schwinn Tailwind electric bike review