2008年诺贝尔生理学或医学奖分别授予德国和法国科学家以表彰他们在发现了人乳头状瘤病毒(HPV)和艾滋病病毒(HIV)方面的成就.如图表示HIV浓度与T细胞浓度的关系,下列叙述正确的是( )
①HIV最初侵入人体时,人体的免疫系统可以消灭大多数病毒
②HIV浓度与T细胞浓度总表现出负相关关系
③HIV攻击T细胞,这不会影响人体体液免疫能力
④艾滋病患者若不进行治疗,大约能生存9年时间.
A:①②
B:①④
C:②③
D:③④
Mr. Jackson is a teacher of science in a middle school. His students like his classes because his classes are very interesting. They can learn a lot in his class. The students can make(制作)many things. His little son Val also likes making things. He makes lots of machines(机器), such as a machine like a man. It can do the job that is dangerous(危险的)for people to do. He says, “I want to be a scientist.”根据短文内容,选择正确答案。
2016年暑假,某大学生骑自行车进行了如右图所示线路的旅行,读图回答问题。