填空题

Questions 47 to 51 are based on the following passage.
The world famous Loch Ness monster, known affectionately as "Nessie" by most people and by the scientific believers goes back a long, long way, the first recorded sighting being by no less a person than a holy saint. The saint was St. Columba and the year 565 AD.
When Columba was travelling in the Loch Ness area converting the Picts, his biographer, St. Adamnan, tells the story of the driving away of the monster by the power of prayer. Whilst on the banks of Loch Ness, St. Columba came upon some Picts burying a man who had been ravaged by, according to them, a "monster of the water". St. Columba miraculously restored the man to life by laying his staff across the man’s chest.
The next time that any reference to the monster surfaced, was in a letter to The Scotsman newspaper in 1933 from a Mr. D. Murray Rose. He tells of a story in an old book that spoke of the slaying of dragons and: "It goes on to say that Fraser killed the last known dragon in Scotland, but no one has yet managed to slay the monster of Loch Ness lately seen."
It was also in 1933, a time of depression and general misery that Mr. and Mrs. Mackay, owners of the Drumnadrochit hotel were travelling along the new road. According to their account they saw in the centre of the loch "an enormous animal rolling and plunging". Cynics may say that being the owners of the Drumnadrochit hotel, this couple may well have wanted to see a monster but apparently they did not tell this story widely, although they did tell it to a young water bailiff in Fort Augustus who happened to be a correspondent for the Inverness Courier newspaper.
Since then to the present day there have been many accounts of sightings. Such "evidence" as film footage of Nessie’s humps travelling across the loch and the famous "Surgeon’s" photograph taken by R. K. Wilson in 1934 have all since turned out to be fakes.
Sonar surveys of the loch using the latest equipment have failed to find any conclusive evidence of Nessie’s existence, but neither have they proved that she doesn’t exist. Some accounts may well have been sighted through the bottom of a whisky glass, but there are still a remarkable number of eye witness accounts that ring true.
How did Mr. D. Murray Rose get to know about the Loch Ness Monster