Randomize every 3rd question?

I'm making a survey that asks participants to do 10 tasks, 3 times each. After doing each task they need to answer the same two questions. I'd like to time how long it takes the participants to complete each task so I'm thinking of putting the task prompt in its own block, then timing the time to click "Next." Then they would answer the two questions in the next block. Then start over with a new task.
Basically it should have blocks in this pattern (but the lettered blocks need to be randomized):
A 1 2 B 1 2 C 1 2 D 1 2 E 1 2 F 1 2 G 1 2 H 1 2 I 1 2 J 1 2
(And bonus points to randomize the x3 repeat of the 10 tasks).
Can't quite figure out how to do this with the randomizer without presenting the task and questions in the same block. Is there some subblock method?
Thanks!