【正确答案】 A

【答案解析】[解析] before，from和since与quite recently连用不符合语法；before quite recently一般要与过去完成时连用；from (since) quite recently一般要与现在完成进行时连用。until用在否定句中表示“直到……才”之意，例如：It was not until the beginning of the century that man began to realize that it was the brain not the heart that was the center of mind. 直到本世纪初，人们才逐渐认识到，是大脑而不是心脏是思维活动的中心。由此可见，A项是正确答案。