Promotion is not based on the ___ (long) of employment only.

问题描述:

Promotion is not based on the ___ (long) of employment only.
括号中的词变为适当的形式填入空白处,略作说明,顺便翻译一下句子.

Promotion is not based on the (length,长度) of employment only.
升职不仅仅是以受雇的时间长短来作为基础的.
这里要填long的名词形式.