单项选择题
| Issac Newton was (41) great English Scientist (科学家), (42) when he was thinking hard about his work, he often forgot (43) things. One morning Newton got up early. He began (44) at once. He worked on a very difficult problem. He was still thinking about it hard when it was time (45) breakfast. Mary brought a pan of water and an egg to his room. But Newton wanted to stay by (46) and said to Mary, "You can put the egg on the table. I’ll boil (沸腾，煮) it myself." Mary put the egg beside Newton’s watch on the table and said, "You must boil the egg (47) four minutes and then it will be ready." Then she went out of the room. But when she went into the room again an hour (48) , she saw him (49) by the pan, and having the egg in his hand. He had put the watch in the pan and was boiling it. But he didn’t know (50) he was doing. |