"Spot sb doing something" emphasizes "suddenly seeing someone doing something" and emphasizes that the action is in progress; "spot sb do" emphasizes "seeing someone do something" and emphasizes the completion or whole process of the action. The specific use should choose the appropriate expression according to the context and expression intention.
Understand through the form? Find someone doing something. Right? ：
Okay, last wave? Find someone doing something. What is the specific difference? : difference 1: action continues vs. action happens spot someone does something: emphasize that someone is doing an action. I saw him walking his dog in the park. I noticed that he was walking his dog in the park. )
Ex. 2: She found her friend studying in the library. She found her friend studying in the library. )
Spot sb do: emphasize that someone has done an action, but don't emphasize its progress. We found the children playing basketball in the backyard. )
Example 2: The teacher found that the students cleaned the classroom after school. The teacher noticed that the students cleaned the classroom after school. )
Difference 2: Accidental discovery and purposeful search to find someone doing something: Accidentally finding someone doing something, usually at a specific time or place. When we were walking in the forest, we found a deer grazing on the grass. While walking in the forest, we happened to find a deer grazing on the grass. )
Ex. 2: During the performance, he found his sister singing in the choir. He happened to find his sister singing in the choir during the performance. )
Spot sb do: deliberately find and find that someone is doing something, emphasizing a specific goal. The detective found that the suspect was stealing the precious painting. The detective noticed that the suspect was stealing valuable paintings. )
Ex. 2: Last night, we found a famous person dining in this restaurant. Last night, we found a famous celebrity eating in a restaurant. )
Difference 3: The emphasis is different. Find out that someone is doing something: the focus is on the action itself. She found her daughter playing the piano very well. She noticed that her daughter played the piano very well. )
Ex. 2: They found a group of tourists taking pictures near the landmark. They found a group of tourists taking pictures near the landmark. )
Pay attention to observed action results or simple facts. We found a meteor last night. )
Ex 2: He found a spider crawling on the wall. He found a spider crawling on the wall. )
Difference 4: action state vs action moment spot sb does something: emphasizes the continuous state of action. They found their neighbor repairing the car all morning. )
Example 2: We found the gardener watering the plants in the garden. We saw the gardener watering the garden. )
A momentary or brief action that emphasizes action. She found her friend waving to her from a distance. She saw her friend waving to her from a distance. )
Example 2: The photographer found a rare bird flying by and quickly took a picture of it. The photographer found a rare bird flying by and quickly took a picture of it. )