问题
选择题
__________ Spring Festival we have a big family dinner. [ ]
A. About
B. In
C. On
答案
答案：C
搜题请搜索小程序“爱下问搜题”
__________ Spring Festival we have a big family dinner. [ ]
A. About
B. In
C. On
答案：C
的阻值为20Ω。当
断开，
、
闭合时，电流表的示数为0.45A。求：
的阻值；