Grammar exercise 1 of 2 语法练习1
Use 了 as “Video lesson: 了 in set patterns, and 了 for a change (le) in Mandarin Chinese grammar” explains it, through 9 items over 6 of its example sentences: fill the gap where the word was taken out, and put the words of each sentence back in order.
Video lesson: 了 in set patterns, and 了 for a change (le) in Mandarin Chinese grammar
9 items. Each one you miss comes back later in the same sitting.