A train left (for) london two hours ago 为什么加for

My uncle left for London two weeks ago.句意不变 the manager left two hours ago.the manager____ ____ ____ for 1.We () here two hours ago.We () here for tow hours A.have a Mr.Smith ___here for about two hours.A.has left B.left from they have been here ___ two hours ago.A.for B.since C.before he left here two hours ago Two tickets for London We ____ here two hours ago.We ____ here for two hours. I play football for(a )two hours 用SINCE或FOR填空 ( )3hours ( )two hours ago ( )we were young ( ) It has kept (raining) for two hours.为什么rain要加ing? I have a basketball for two hours.对for two hours进行提问