--It is really fun to hike and I often go hiking in the forest.--But hiking alone in the forest ______ be very dangerous.

I am fond of my sister but she has one serious shortcoming. She _________ be really stubborn.

--Have you decided where to go for your summer vacation? --Not yet. We_________ go to Mount Lu. It is a good place for vacation.

    One of the few things you ______ say about English people with certainty is that they talk a lot about the weather. 

Mr Black   be at home because she called me from England just now.