He has behaved in the most extraordinary way recently. I wonder what can_____ his actions.
Oh, it's you, I'm sorry I ____know you ____here.
Wherever I ____these days. I always carry my umbrella.
It is five years since my dear aunt _______ here.
It ________ nearly two weeks ______ I had received his letter.
----This returned Chinese scholar has become one of the top experts in this field.----Yes,I know him very well.He____in Africa with animals for eight years.