The water in this river is harmful because It’s a ______ river.

E-mail is much ______than long-distance calling.

---Mum , I think I’m _______ to go back to school .  --- But the doctor says you must stay in bed for two more days .

I didn’t sleep ______last night.  I feel tired now. 

Paul isn’t as ______ as Sandy. He often makes mistakes in his homework.