I didn't stand firm and I tumbled.

我没有站稳，摔倒了。

youdao

I didn't stand firmly and I tumbled.

我没有站稳，摔倒了。

youdao

I tumbled all the way down and somehow managed to roll into a crouching position, sprang to my feet and kept running till I hit the bottom ramp.

我跌倒并沿著斜坡向下滚去，中途我顺利得转换成蹲伏的姿势，我赶紧跳起来，继续沿著斜坡向下跑去，直到跑到最底层的那个斜坡。

youdao

It was just about dark when my cameraman Scottie McWhinnie and I tumbled out the back.

CNN: Digging in with the Marines

At one point I stopped for a swig of water, and when I slapped at the whining mosquitoes that danced on my neck and hands, I slipped and slid over some tumbled pieces of rock, grabbed at branches to stop my fall, and landed just in front of a bas-relief of warriors, maidens and fish alive in stone.

BBC: Piecing together puzzles in Cambodia

No matter how quickly I twisted, tumbled, and turned, there was nary a stumble.

CNN: A Ferrari for your desktop: Gateway's 'ultimate enthusiast' PC