没看的占：1-13=23，
没看的是已看的：23÷13=2．
故判断为：正确．
In my home breakfast is ______ at 7 o’clock, which has ______ unchanged for 20 years.[ ]
A. ordered; lasted
B. served; remained
C. served; appeared
D. ordered; developed
要使直流电动机能连续转动，必须设法使通电线圈刚转过平衡位置时，自动改变 _________ ，完成这一任务的装置叫做 _________ ．
