Of the three girls, Mary sang             

 If you want to know the meaning of the word______, you’d better look it up in the dictionary.

—Well, you've come back! ________ did you stay in Shanghai? — For about seven days. I really enjoyed myself.

 This is the book ______we are looking for. 

---Can I help you?---Well, I’m afraid the box is _______ heavy for you, but thank you all the same.