[解题导语] 经过对8,600多人进行了为期六周的实验表明：网络智力游戏并不能增长智力。
1．It can be inferred that the online brain games mentioned in the text are________.
A．costly B．unreliable
C．illegal D．effective
解析：推理判断题。根据文章第1段的people who played online games designed to improve their cognitive(认知的)skills didn't get any smarter；第3段的the people who did the brain training didn't do any better on the test after six weeks than people who had simply been on the Internet；第4段的if you're expecting (these games) to improve your IQ，our data suggests this isn't the case可知：玩网络智力游戏并不能真正提高智力。
答案：B
