白纸

yào yòng bái zhǐ hēi bǐ yǐ què bǎo fù zhì qīng xī

要用白纸黑笔，以确保复制清晰。

Use a black pen on white paper to ensure good reproduction.

liǎng zhāng bái zhǐ

两张白纸

two clean sheets of paper

shè yǐng bǐ sài de cān sài zuò pǐn yīng gāi biǎo tiē zài bái zhǐ shang

摄影比赛的参赛作品应该裱贴在白纸上。

Entries to the photography competition should be mounted on white paper.

tā jiù xiàng yī zhāng bái zhǐ

她就像一张白纸。

She is like a blank sheet of paper.