【单选题】How did the Beatles differ from the Stones?
A.
Their unique hair style — mop-top.
B.
Their early songs were about the innocence of young love.
C.
They had a chance to prove themselves at a Royal Variety Show attended by the Queen Mother and Princess Margaret.
【单选题】关于链条传动,以下说法哪一种是不正确的( ):
A.
链传动中常用滚子链,噪声较大,而在希望传动装置具有振动和噪声低的场合则可以使用无声链
B.
:链轮的轮齿数过少则磨损增大且有冲击运动,传动不均匀
C.
:链轮的齿数尽量采用偶数,而链条的节数尽量采用奇数
【单选题】How the massive stones were brought here from hundreds of miles away remains a _________.
【判断题】21 世纪中叶,我国的人均国民生产总值将达到中等发达国家水平
【判断题】垂直传播即母婴传播,指病原体由亲代传至子代,包括经生殖细胞传播、妊娠期经胎盘传播、分娩期经产道传播及产后经哺乳传播等。( )
【单选题】根据我国现代化建设“三步走”发展战略,到21世纪中叶我国将实现的目标是: