Definition
To react or respond to an event or situation with speed or slowness.
反應迅速／遲鈍
He was quick off the mark to sell all his stocks when the market started to fall.
當市場開始下跌時，他迅速賣掉了他所有的股票。
She is always quick off the mark, able to seize new business opportunities quickly.
她總是反應迅速，能夠迅速抓住新的商業機會。
He was slow off the mark at the start of the race, but he soon caught up.
他在比賽開始時反應遲鈍，但很快就趕上了。