Thanks for your reply. I applied the way how it is grouped in the tutorial and it works fine. Now, participants from group A are able to see different conditions with different items.
My another question is also about how to randomize the conditions within a group. To be more clear, for example, in the tutorial, the participant from group A will see plural inflection of the first item, then singular inflection of the second item and so on, as stated in the table. What I want to do is if a participant sees the plural inflection of the first item, then it should be possible for them to see the plural inflection of the second item, not necessarily the singular. This should also apply to all items; they can see either plural or singular inflection of every item. After seeing all the items (let’s say 30 items in total), of course, the number of each inflection they see must be balanced (15 singular, 15 plural) but there should be variation in inflections each participant sees. How can I implement such a structure? Thanks for your help.