Randomly select some trials from two distinct groups
I am trying to set up a very simple experiment but I stuck in a practical issue. I am supposed to ask my participants to indicate whether a pair of words are opposites or not. I am planning to present two sets of pairs. The first set will refer to certain adjectives (e.g., competent - incompetent) and the other set will refer to emotions (e.g., happy - sad) and colors (e.g., black - white). There are a lot of pairs and I want to randomly show my participants, some but not all the pairs. Say, that I want to show them 10 pairs. But, I want seven out of these 10 pairs (i.e., 70%) to come from the first set and the remaining three (i.e., 30%) of the pairs to come from the second set. Although I tried to find a solution from the discussion forum or from the instructions in opensesame page (for example by using the command "slice" or through "weighing") I could not find a way how to address this issue. I would appreciate any assistance.
PS. this is an exploratory study so there is not necessarily a "correct answer". I only want to see how people construe specific pairs of adjectives and I want to include pairs of emotions or colors as "manipulation checks". As can be seen below the example of my block loop is quite simple: