(2006·浙江)

When ________ different cultures, we often pay attention only to the differences without noticing the many similarities.

[　　]

--- Did, you remember to give Mary the money you owed her?

--- Yes, I gave it to her ________ I saw her.

[　　]

--- ________ he have been chosen as captain of the football team?

--- Yes, he ________.

[　　]

--- Jack came to work last Saturday, but no one has seen him since.

--- ________ he have gone abroad?

[　　]

John, you ________ play with the knife; you hurt yourself.

[　　]

Peter ________ come with us tonight, but he isn't very sure yet.

[　　]

(2005·江苏)

--- The woman biologist stayed in Africa studying wild animals for 13 years before she returned.

--- Oh, dear! She ________ a lot of difficulties!

[　　]

(2005·天津)

I ________ have been more than six years old when the accident happened.

[　　]

(2005·山东)

He paid for a seat, when he ________ have entered free.

[　　]

(2005·广东)

--- I've taken someone else's green sweater by mistake.

--- It ________ Harry's. He always wears green.

[　　]