皮皮学,免费搜题
登录
搜题
【单选题】
听力原文:About 10 percent of Europe's present-day population seems to be resistant to HIV -- a significantly higher proportion than on other continents. Researchers have traced this immunity to a genetic mutation that seems to have appeared some 2,500 years ago, and that protects white blood cells against penetration by HIV. From the mid-14th century through the 17th century the prevalence of the mutation increased, in tandem with repeated outbreaks of the plague. The researchers suggest that the mutation protected against the disease, which culled the population of people who lacked it. Which of the following is true about the immunity to HIV?
A.
It is partly resistance to the mutation.
B.
More Europeans have it than the people on other continents.
C.
It is the result of outbreaks of the plague.
D.
It is a mutation that protects white blood cells.
拍照语音搜题,微信中搜索"皮皮学"使用
参考答案:
参考解析:
知识点:
.
..
皮皮学刷刷变学霸
举一反三
【单选题】古代,各种实物货币虽然各有缺点,但是仍然被人们接受使用的主要原因是什么?
A.
由于工艺水平落后,人们无法克服
B.
经贸量不大
C.
缘于人们的习惯
D.
缘于当地的文化传统
【简答题】___是构筑智能交通系统综合平台的最底层支撑。
【单选题】制绒前粗抛的目的是( )。
A.
去除黏附的小颗粒和杂质
B.
去除机械损伤层
C.
制备绒面
D.
去除金属杂质和氧化层
【简答题】v. 赔偿;补偿; 弥补
【简答题】v. 补偿,赔偿 2. 弥补,抵消
【判断题】散客行李员执行送行李服务时,可以与客人一同乘坐电梯。
A.
正确
B.
错误
【判断题】某系统在电动机轴端拾取反馈信息,该系统属于半闭环伺服系统。
A.
正确
B.
错误
【判断题】在代开增值税专用发票之后,小规模纳税人如果专用发票需作废或冲红,其已缴相应税款必须退还。( )
A.
正确
B.
错误
【简答题】________v. 补偿,弥补,赔偿
【单选题】某系统在电动机轴端拾取反馈信息,该系统属于()。
A.
开环伺服系统
B.
半闭环伺服系统
C.
闭环伺服系统
D.
定环伺服系统
相关题目: