这个Wi-Fi信号不稳定，有时会变得无法连接。

This Wi-Fi signal is unstable and sometimes becomes ___unreachable.

我的医生24小时都可以联系到。

My doctor is always ___reachable by phone day or night.

只要努力工作，升职的目标是可以实现的。

With hard work, a promotion is definitely ___reachable.