我的电脑最近经常死机，这些问题必须尽快解决。

My computer keeps freezing lately, and these ___problems need to be fixed soon.

这道物理问题需要用到牛顿第二定律。

This physics ___problem requires the use of Newton's second law.

他在学习新语言时遇到了很多困难。

He faced many ___problems while learning the new language.

说服孩子们早睡是这个家庭最大的难题。

Getting the kids to bed early is the biggest ___problem in this family.