根据提示用本部分所学词汇的正确形式完成下列短文（每空一词）Sports like American football and ice hockey get most of the attention when it comes to concussions (脑震荡) and other forms of brain injury. But soccer is a(n) 【小题1】 (激烈的) sport for which the head can be as important as the foot.
Heading the ball is a key soccer skill. But a new study finds that players who head the ball frequently are more likely to suffer 【小题2】 (长久的) brain injury and damage their memory than players who are less likely to use their heads.
“For many people, it’s beyond belief that a slight injury could be a problem,” said Dr. Michael Lipton, an expert of neuroradiology (神经放射学) in New York City.
Lipton and his team interviewed 37 adult soccer players from New York City and took high-tech scans (扫描) to 【小题3】 (检查) their brains. They also asked the players how often they played soccer and how often they headed the ball, and they gave the players some neurocognitive tests.
The 【小题4】 (结果) was that the researchers found no link between small amounts of heading and players’ attention, ability to control their 【小题5】 (速度) when they move, or ability to manage complex thinking tasks. However, Lipton warned players not to ignore the possible risks of heading the ball too many times. Players could safely head the ball 885 to 1,550 times a year. It took almost 1,800 times a year for players to have trouble with their memory.
