She doesn't know _________________ made her daughter so sad this morning.

We shouldn’t spent our money testing so many people, most of _____are healthy

Don’t forget to bring a dictionary next class. ___. I didn’t catch what you said.

She brought with her three friends, none of ______ I had ever met before. 

____________ with many teenagers, Zhou Dongyu who comes from the new movie Under the Hawthorn Tree prefers pop music to classical music.