People who committed suicide found their life very nasty gloomy and painful. => This is ok. => Alternative: People who committed suicide found their life to be very nasty, gloomy and painful. People who committed suicide considered their life very nasty, gloomy and painful. in what restaurant do you usually have breakfast? => This is ok. => Alternative: At which restaurant do you normally have breakfast? Did you like riding a bike when you were a child? => This is ok. Who else were riding in the car beside you? => This is ok.

(The) people who had committed suicide (usually) had found their lives unbearable and too painful. In what restaurant do you usually have breakfast? > ok > Type of restuarant , as in Japanese . Western, Indian, etc. "In which" > the restuarent you normally go to. Did you like riding (a) bike when you were a child? > Ok Who else were riding in the car beside you? > Not good 1)" Who" is singular , therefore use "was" 2) "beside" means "next to/at the side of ..) Who else was riding in the car besides you? > "besides"> "in addition to .." Who else was with you in the car ?