TRAPDOOR TRANSLATION: Using Trapdoor in Textivate to make a multiple-choice translation rebuild activity

(Please scroll down to the bottom of the post to try the activity for yourself.)

This post refers to the optional text-based activity, Trapdoor, as introduced in this blog-post / user-guide:

The end result of this blog post also requires you to include a parallel text translation in the L1 (which may or may not be divided into "chunks" by adding vertical pipes as in the example shown). See this user-guide on parallel texts and how to add them to your resource:

The procedure...