某校从参加高一年级期中考试的学生中随机抽出60名学生，将其数学成绩(均为整数)分成六段40,50)，50,60)，…，90,100后得到如图所示的频率分布直方图，观察图形的信息，补全这个频率分布直方图后，估计本次考试中的平均分（统计方法中，同一组数据常用该组区间的中点值作为代表）   （   ）

2014年寒假期间，八年级学生小翠在QQ上结识了一个网友“暖冬”，“暖冬”多次要求小翠将她家的详细地址、电话号码等告诉他，还多次约她见面，外出游玩。对此，小翠的正确做法是    (    ) 

DNA分子中，____ 的排列顺序代表了遗传信息．

长达三百多年的罪恶的“三角贸易”对欧洲资本主义发展所起的主要作用是（    ）

Tang Hai is chatting with his e-pal David on QQ (T: Tang Hai   D: David)
D: Hi. How is it going these days?
T: Pretty good! We celebrated our Dragon Boat Festival(端午节) last week.
D: Dragon Boat Festival?1
T: To remember an ancient Chinese poet(诗人)。
D: How do you usually celebrate it? 
T:2 But this year, we did something more interesting.
D: What did you do?
T: Our school had a Dragon Boat race.
D:3 who won the race?
T: Our class.
D:4
T: Thanks a lot. I hope you can come to China sometime.
D:5 I'm interested in Chinese traditions. Tell me more about them next time.
T: Ok, I will. See you.
D: See you!