Sentence examples for must be working from inspiring English sources

"must be working" is a grammatically correct and commonly used phrase in written English.
It is used to express that something is necessary or expected to be functioning or operating. Here are a few examples of how it can be used: 1. "In order to succeed in this job, you must be working diligently and efficiently at all times." 2. "The engine must be working properly for the car to run smoothly." 3. "I think the air conditioner must be working too hard - it's making a strange noise." 4. "We can't open the store until all of the machines and equipment are checked and confirmed to be working." 5. "The hotel must be working to address their customer service issues, as I've noticed a significant improvement in my recent stay."