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