playground是什么意思？

A study in Sweden indicated that kindergarten children who could play in a natural environment had less illness and greater physical ability than children used only to a normal playground.

A good playground helps kids develop their physical abilities

While that may make suborbital travel safer, it would add significant cost and complexity to an emerging industry that has until now operated largely as the playground of billionaires and dreamy engineers.

How Virgin Galactic, regulators and the public respond to this most recent tragedy will deter mine whether and how soon private space travel can transcend that playground.

As they walk around a playground or other area, text, video or audio pops up at various points to help them try to figure out why aliens were in the schoolyard.

How Virgin Galactic, regulators and the public respond to this most recent tragedy will determine whether and how soon private space travel can transcend that playground.