Why did the dinner party start so late last night?— It was _____ that caused him to serve dinner an hour later than usual.

Listen! Someone is playing ____piano in the music room.—Wow! ______ beautiful music! I like it very much.

People from the West like to use these words in cases ____ some people in Asia may not think it necessary.

— Why does the Lake smell terrible? — Because large quantities of water _____. [ ]

I’ll try whobroke the window.