孩子们在草地上开心地翻跟头。

The kids are happily doing ___somersaults on the grass.

孩子们在草地上开心地翻着跟头。

The children are happily doing ___somersaults on the grass.

公司突然改变了环保政策，这种180度大转弯让员工们感到困惑。

The company's sudden ___reversal on environmental policies left employees confused.