For c = -1 To -2 Step -1
For d = 1 To 2
b = b + 1
Next d
a = a + 1Next c初始值 a = 0 , b = 0。我们规定外层的 c 循环为大循环，内层的 d 循环为小循环。【第一次大循环：c = -1】进入小循环：第一次：d = 1 , b = b + 1 = 0 + 1 = 1。第二次：d = 2 , b = b + 1 = 1 + 1 = 2。退出小循环：a = a + 1 = 0 + 1 = 1。【第二次大循环：c = -2】进入小循环：第一次：d = 1 , b = b + 1 = 2 + 1 = 3。第二次：d = 2 ...
