Here are some common English expressions you can use when guessing.
It looks like
you’re new here.
It looks like you
don’t know what happened.
she knows the answer.
it’s over 9 A.M now.
If I had to take a guess, I’d say
he wants to quit his job.
it’s going to rain.
you’re doing it wrong
be right about it.
you are over 30 years old.
It’s difficult to say, but I think
this is the best English course.
I’m not really sure, but I think
this is the last morning train.