单项选择题

With the Met Office predicting a summer heatwave, Macmillan Cancer Relief this week (1) its customary warning about the sun’s ultravioiet rays: (2) , it says, for the huge rise in skin cancers affecting 70,000 people a year. (3) a hat and long-sleeved shirt, it advises, keep in the (4) in the middle of the day, and slap (5) suncream with a protection factor of 15 or above.
We all know it (6) ; it’s the message that’s been drummed into us for the past 20 years. Too much sun (7) . But now there’s a fly in the suntan lotion, complicating the message’s clarity. It comes (8) a thin, quietly-spoken and officially retired Nasa scientist, Professor William Grant, who says that sun doesn’t kill; in act, it does us the world of (9) . What’s killing us, he says, is our (10) with protecting ourselves from skin cancer.
Grant is trying to turn the scientific world (11) down. Talking to me on a trip to Britain this week, he (12) his startling--and at first appearance off-the-wall new calculation that (13) excessive exposure to the sun is costing 1,600 deaths a year in the UK from melanoma skin cancers, (14) exposure to the sun is the cause of 25,000 deaths a year from cancer generally. In other words, one sixth of all cancer deaths could be prevented (15) we sunned ourselves a little more; in comparison, the melanoma (16) is insignificant.
The reason is vitamin D. Grant, the director of the Sunlight, Nutrition and Health Research Centre (SUNARC) he (17) in California a year ago, says that he and other scientists have (18) vitamin D deficiency as a key cause (19) 17 different types of cancer including melanoma, osteoporosis, diabetes, multiple sclerosis and other neurological (20) .

18（）

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