It ________be the vocabulary that caused you the problem in the exercise because you know a lot of words.                                                  

It is usually warm in my hometown in April, but it ________ be rather cold sometimes.

Jenny doesn’t agree with her father, but she ________ that to his face.

—You shouldn’t have shouted at your mother. It really hurt her.  —Exactly. I ________ crazy at the time. 

Delta, the American airline, is sometimes jokingly explained “Don’t expect your luggage to arrive” because it ______ be very slow.