leave
vt.离开；留下；遗忘；委托 ,及物动词,可以不加介词,后面加宾语
vi.离开,出发；留下 不及物动词,后面需要加介词,加宾语.
及物动词,离开 If you leave a place or person,you go away from that place or person.离开例：He would not be allowed to leave the country.他不准离开这个国家.
They are leaving Beijing.来表示他们将要离开北京 也是对的.
They will leave Beijing 也成立