With the Met Office predicting a summer heatwave, Macmillan Cancer Relief this week (1)_____ its customary warning about the sun's ultraviolet 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 fact, 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)_____. A．issued B．claimed C．declared D．announced