---What did you say to Julia? I saw her crying in the dormitory alone. --- It ______ my fault. We talked happily when I was with her in the classroom.

Helen ______ go on the trip with us, but she isn’t quite sure yet. 

- Do you know where my address book is?　　　　- It________ be in the hall cupboard. I think I saw it this morning.

---I’ve told her many times, and she still forgot about it!---I understand. It’s true that she___ be very forgetful sometimes.

He is a poorly learned man, but he acts as if he ______.