She is organized, friendly to people, hard-working and clever. _______, I can’t speak too highly of her.

It isn't so much whether he works hard; the question is whether he works _____.

—— Do you go there ＿＿＿bus? —— No, we go there ＿＿＿a train. 

This book _________12 units, _________ the unit of Music.

Pleasant music is often played_____classes to make students refreshed and relaxed for a while.