放映用物镜应能耐热，故通常不使用胶合透镜。

With the objective to heat should be shown. So don't usually use agglutination lens.

youdao

用钢笔写信，所以要有“用”字，故加with。

I have a pen to write a letter with.

youdao

用钢笔写信，所以要有“用”字，故加with。

I have a pen to write a letter with.

youdao