Can two people with - blood type have a baby?

No, two parents with - (O) blood type cannot have a baby with a + (A or B) blood type. This is because the - blood type is recessive, meaning that both parents must have the - gene for their child to have that blood type. A person with a + blood type must have at least one + gene, so if both parents have -, they cannot pass on a + gene to their child.