Yes, it is. Sometimes conditional sentences do not follow the standard first, second and third conditional patterns but can include different verb forms. Sometimes you can even see conditional sentences "without"! if of another conditional word, such as "in case" or "unless".
For more information and practice:
1 read the following explanation
2 do this exercise
3 and then this one
4after that look at the explanation for conditional sentences without if
Finally, read the information and do the exercise!
