Busy Teacher has a lot of worksheets to help students practice tenses. This subsection, which has
7 worksheets, is for the Future Perfect Continuous tense. Many of the available worksheets posted here were made as review activities.
This is actually a test of all the future tenses which means that it is most appropriate for intermediate and upper intermediate students who have had plenty of practice using them. Unfortunately, there is no answer key included; since there are only ten sentences, creating an answer key should not take too much time. You can also change the worksheet to better reflect what you have been practicing in your classes. Another worksheet posted here is very funny but not appropriate for all classes. On the last page of
this worksheet are sentences about drinking that use every single tense. This is probably best for adult classes although with some alterations, you could probably change the main topic from drinking to something more student-friendly. If those are not what you are looking for or if you are interested in a different tense altogether, look at the main tense section for worksheets or ideas.