---When did you learn the news that Obama made a trip to Canada as President?- was on

问题补充：

---When did you learn the news that Obama made a trip to Canada as President?

--- was on my return.

A. That

B. It

C. There

D. This

答案：

A. That

(答案→)B. It

C. There

D. This

解析：考查强调句型。 was on my return是强调句型的省略句，补充完整应是it was on my return that I learnt the news that Obama made a trip to Canada as President.所以选B。