The host poured the tea into the cup and placed it on the small table in front of his guests,who were a father and his daughter,and put the lid on the cup with a clink.Obviously thinking of something.he hurried into the inner room,leaving the thermos  on the table.His two guests heard a chest of drawers opening and rustling.     They remained sitting in the sitting room,the ten-year-old daughter looking at the flowers outside the window,the father just about to take his cup,when the crash came,right there in the sitting room.Something was hopelessly broken.     It was the thermos,which had fallen to the floor.The girls looked over her shoulder suddenly,shocked, staring. It was mysterious;neither of them had touched it,not even a little bit.True.it hadn't stood steadily when their host placed it on the table,but it hadn't fallen then.     The crash of the thermos caused the host,with a box of sugar cubes in his hand,to rush back from the inner room.He looked foolishly at the steaming floor and blurted out. "It doesn't matter! It doesn't matter!''     The father started to say something.Then he said in a low voice,"Sorry I touched it and it fell."     "It doesn't matter,"the host said.     Later,when they left the house,the daughter said,"Daddy,did you touch it?''     "No.But it stood so close to me."     "But you didn't touch it.I saw your reflection in the window .You were sitting perfectly still."     The father laughed."Then how would you explain the cause of its fall?"     "The thermos fell by itself , The floor is uneven. It wasn't steady when Mr. Li put it there. Daddy,why did you say that?"     "That won't do,girl.It sounds more acceptable when I say I knocked it down.There are things which people accept less true it sounds."     The daughter was lost in silence for a while.Then she said,"Can you explain it only this way?"     "Only this way."her father said. From the passage,we can see the reason why the thermos fell was that_.
the table was too small the father sat too close to the thermos the father wanted to help himself with some water something impossible to explain happened