This is because the declining-balance method provides an "automatic"residual value. 这是因为余额递减法本身已自动考虑了残值。
Accelerated depreciation shall generally be calculated using only the double reducing balance method or sum-of-digits method. 企业加速计算折旧，一般应只限于采用双倍余额递减法或年数总和法。
