我对改革进展缓慢越来越感到沮丧。

I'm growing increasingly ___frustrated at the slow pace of reform.

许多员工对公司不透明的晋升流程感到沮丧。

Many employees feel ___frustrated by the company's opaque promotion process.

会议被无故取消，这让我们深感沮丧。

We were deeply ___frustrated that the meeting was canceled without explanation.