You may just give me a call or drop in, will do.
_____the teacher couldn’t understand was _____ fewer and fewer students showed interest in his class.
-- You look so tired.--- Yes. I _____ the house all the morning. But I’m finishing it soon.
Police in America have stepped up their search for a fifteen-year-old boy who went _____ three days ago.
There are _____ flights between the two cities, _____ it convenient for people in one city to travel to work in the other.
Though faced with so many difficulties, they are _____ about their future.