Use the right prepositions or adverbs: Every morning regularly... ten o'clock, when her lecture was... Jean came... the

Every morning regularly at ten o\'clock, when her lecture was over Jean came into the room, where I was already at work. Her careful, accurate work was of great help to me. She prepared hundreds of slides which it was necessary to examine. She was very careful and never made a mistake. Her presence stimulated me greatly.  At one o\'clock we had lunch in the laboratory. On the seventh day, as we worked silently I heard a step and turned round. Professor Challis stood in the doorway. \"I thought I\'d look in, Robert, to see how you were getting on.\" I rose at once and introduced him to Jean. He bowed to her in his old-fashioned manner. I understood that he liked her. After that he came regularly to visit us, often at the lunch hour. He sat on a chair watching us with his bright eyes. He often told us about his life as a young student in Paris at the Sorbonne, where he worked under the great Duclaux.