请问调用系统时间为何全都相同？

@璐村惂鐢ㄦ埛_000076K馃惥 off
set filename=E:\Back\defrag.log
echo --------------------------------- >> %filename%
for %%n in (C: D: E:) do (
echo %date% %time%: >> %filename%
echo Ready defraging %%n driver,please waiting ... >> %filename%
echo Starting... >> %filename%
start "VolumesManage" /wait /B defrag %%n /U /V
echo %date% %time%: >> %filename%
echo %%n driver has Ended! >> %filename%
echo. >> %filename%
)