19世纪末20世纪初在美国形成的一种学制是( )
A.单轨学制
B.双轨学制
C.分支型学制
D.1951年学制
参考答案:A
There are ______ in my school as in your school. [ ]
A. as four times many students
B. four times students as many
C. four times many students as
D. four times as many students
游标卡尺和螺旋测微器是两种常用的测量长度的精密仪器。如图甲所示的游标卡尺,主尺的最小分度是1mm,游标上有20个小的等分刻度,图示状态的读数是___ _____mm;用如图乙所示螺旋测微器测量一根金属丝的直径的读数是____________mm。