Around the AD 1000's, a man ____ (call) Bi Sheng in China invented a more flexible (灵活的) system of printing.
①稀硫酸 ②甲烷③小苏打 ④熟石灰
关节是能活动的骨连结,在运动中起支点的作用.如图是关节结构模式图,下列说法正确的是( )
判断对错.
1.24-0.24÷8
=1.0÷8
=0.125