翻译成英文修改用词及语法错误使更符合天体物理学术论文要求： To put further constraints on the cause of the absorption line variability it would be interesting to check individual spectra which is beyond the scope of this paper

To obtain more precise constraints on the origin of the variability in absorption lines, it would be of great interest to examine individual spectra. However, this is beyond the scope of the present paper.