I cannot come here as often as I used to
首先 我觉得用come比用be动词好
其次,表事情发生的频率不能用many要用often
最后的do省略
I won't be here as often as usual.
或者 I won't be here as often as I used to.
i cannot be here as often as usually
你的翻译不对.要是按照你的翻译就是《我不能在这里为我做》的意思了
I cannot come here as usually as before.
I can not