_________ isunknown to us all

I got upset yesterday just because you didn’t hand in your homework on time.— Terribly sorry. Ten more minutes, I_____it to you.

Vitamin D helps our bodies make a special chemical，and this special chemical，________，affects our brains，making us feel happy

Why don’t we take a little break—Didn’t we just have______

The bride and groom gave _____ attended their wedding some gifts to share their happiness.