Grammar exercises: Video lesson: 了 in set patterns, and 了 for a change (le) in Mandarin Chinese grammar 语法:了 练习
The example sentences of the article, a few to an exercise, in the order the article shows them. Each exercise takes the point's word out of a sentence for you to fill back in, then gives you the sentence's words to put in order, and an item you miss comes back later in the same sitting.
2 grammar exercises over 20 items.