The term "existing" generally refers to the state of being or the condition of something that exists or has actual being. It means that something is real, tangible, or has some form of reality. However, in the context of time and presence, "existing" doesn't necessarily imply constant presence.
For example, if we say a physical object exists, it means the object is real and can be observed or interacted with, but it doesn't mean it has to be constantly present in front of us. Similarly, if we say a person exists, it means that person is real and has existence, but they may not be constantly present in a particular place or moment.
"Constantly present" would suggest that something is always there without any breaks or interruptions. While some things can be constantly present, like certain natural phenomena (e.g., the sun's rays, the Earth's gravitational pull), many other things have a presence that might be temporary or intermittent.
So, in summary, "existing" refers to having real being or presence, but it doesn't necessarily mean being constantly present at all times.