阅读理解。 The regular use of text messages and emails can lower the IQ more than twice as much as smoking marijuana(大麻). That is the claim of psychologists who have found that tapping away on a mobile phone or computer keypad or checking _ them _ for _ electronic _ messages _ temporarily _ knocks _ up _ to _ ten _ points _ off _ the _ user's _ IQ. This rate of decline in intelligence compares unfavorably with the fourpoint drop in IQ associated with smoking marijuana, according to British researchers, who have labeled(把 ……称为)the fleeting phenomenon of enhanced stupidity as 'infomania'． The noticeable drop in IQ is believed to be the result of the constant distraction of 'always on' technology when employees should be concentrating on what they are paid to do. Infomania means that they lose concentration as their minds remain fixed in an almost permanent state of readiness to react to technology instead of focusing on the tasks in hand. The brain also finds it hard to deal with keeping lots of tasks in motion at once, reducing its overall effectiveness. While modern technology can have huge benefits, excessive(过度的)use can be damaging not only to a person's mind, but to his or her social life. Eighty volunteers took part in clinical trials on IQ damage and 1,100 adults were interviewed. More than six in ten people polled admitted that they were addicted to checking their emails and text messages so that they examined workrelated ones even when at home or on holiday. Half said that they always responded immediately to an email and one in five would interrupt a meeting to do so. Furthermore, infomania is having a negative effect on work colleagues, increasing stress and disagreeing feelings. Nine out of ten polled thought that colleagues who answered emails or messages during a facetoface meeting were extremely rude. Yet one in three Britons believed that it was not only acceptable, but actually diligent and efficient to do so. 1．What does the underlined part mean? A．A person's IQ drops ten points if he or she always checks electronic messages. B. The person who has a higher IQ enjoys checking electronic messages. C. The person who has a lower IQ enjoys checking electronic messages. D. A person's IQ is ten points higher if he or she always checks electronic messages. 2．What happens to people with infomania? A．People with infomania can only concentrate on their tasks in hand. B. People with infomania are addicted to smoking marijuana. C. People with infomania can't respond to technology immediately. D. People with infomania can't concentrate on their tasks in hand. 3. From the passage, we can learn that________. A．about 550 interviewees responded to an email immediately B. about 670 interviewees responded to an email immediately C. about 50 taking part in clinical trials on IQ were addicted to checking emails D. about 16 taking part in clinical trials on IQ refused to answer emails immediately 4．What is the main idea of this passage? A．The regular use of text messages and emails can be compared to smoking marijuana. B. Modern technology can damage a person's mind. C. The regular use of text messages and emails can harm your IQ. D. Electronic messages have side effects on the user's life.