Grammar exercise 1 of 2 语法练习1
Use 吧、吗 as “The sentence particles 吧 (ba) and 吗 (ma) in Chinese grammar” explains it, through 13 items over 7 of its example sentences: fill the gap where the word was taken out, and put the words of each sentence back in order.
The sentence particles 吧 (ba) and 吗 (ma) in Chinese grammar
13 items. Each one you miss comes back later in the same sitting.