The word "probably" is a very common adverb that is used when there is a good chance something will happen. Notice that "probably" is usually placed close to the verb that it modifies.
I’m probably going to go shopping today.
It will probably rain this afternoon.
You probably want some help with this difficult assignment.
The kids will probably want to go to the park later.
It’s probably going to rain all day today.
Use "probably" and "not" when you predict something is not likely to happen:
It’s probably not going to rain today.
They probably won’t be here until later.
He probably won’t get the job he interviewed for.
She’s upset about something. This is probably not a good time to talk to her. Wait until later.
You can also use "probably" for things that may or may not have happened in the past.
Dave isn’t here yet. He probably got stuck in traffic.
Nadine looks unhappy. She probably failed her test.
Our teacher’s hair is all wet. He probably came to school without an umbrella today.
Isabel was late to class. She probably slept through her alarm.
Notice that probably is often a one-word answer to a question or a statement:
A: Do you think the test will be hard?
B: Probably.
A: This car repair is going to be expensive.
B: Probably.
A: They’ve been going out for over four years. Will they ever get married?
It’s probably going to rain all day today.