Sentence examples for was up to from inspiring English sources

"was up to" is a correct and usable phrase in written English.
It is often used to talk about someone's actions or behavior, usually in a past tense. Here are a few examples: 1. "I heard John was up to something last night." 2. "What were you two up to all day?" 3. "I have no idea what she was up to, but it definitely caused a commotion." 4. "We were wondering what you were up to when you suddenly disappeared." 5. "It was clear that he was up to no good with that sly smile on his face." In all these examples, "was up to" is used to describe someone's actions or behavior without specifying exactly what they were doing. It adds a sense of curiosity or mystery to the sentence.