The minimum velocity needed to escape a gravitational field. 逃離引力場(chǎng)所需最短時(shí)間。
In high concentration the shift from the focus of attention is of short duration and relatively infrequent. 在注意力集中時(shí),注意力的焦點(diǎn)轉移是在很短時(shí)間內,而且比較而言是很少發(fā)生的。