一个高中英语单选题----------务必高手帮忙
14、If he had spent more time practicing speaking English before,he _____  able to speak it much better now.
A：will be      B：would be      C：has been            D：would have been
答案是选项,可是我好像从来没听说would be 有虚拟的用法,也许我没学到这个知识点,请高手赐教,这是哪个知识点,