Grammar exercise 1 of 2 语法练习1
Use 谁、什么、哪儿、怎么 as “Repeating question words in Chinese (place-holder question words)” explains it, through 6 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.
Repeating question words in Chinese (place-holder question words)
6 items. Each one you miss comes back later in the same sitting.