这种方法廉价些，因其把微弱曝光的负片放在背板或背纸上作整片。

But the process was cheaper involving a weakly developed negative being placed on back card or paper to appear as a positive.

youdao

这种方法廉价些，因其把微弱曝光的负片放在背板或背纸上作整片。

But the process was cheaper involving a weakly developed negative being placed on back card or paper to appear as a positive.

youdao