problem

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.

我的手机出了点问题，充不进电。

There's a ___problem with my phone—it won't charge.

医生说我需要多喝水来解决这个问题。

The doctor said I need to drink more water to fix this ___problem.

我膝盖有些问题，所以不能跑步。

I have some ___problems with my knee, so I can't run.