Answers:

1. A coffin

2. The child was born before 1776

3. Mount Everest, it just hadn't been discovered!

4. Clara lives in the southern hemisphere.

5. World War I wasn't called "World War I" until World War II.

6. The word "and".

7. They fall in the same year every year, New Year's Day just arrives very early in the year and Christmas arrivesvery late in the same year.

8. The lady was a Justice of the Peace.

9. One thousand nine hundred and ninety dollar bills are worth one dollar more than one thousand nine hundred and eighty-nine dollar bills.

10. Only once, then you are subtracting it from 20.

11. An hour and a half IS 90 minutes.

12. "one word"

13. Penguins live in the Antarctic.

14. Neither, the yolk of the egg is yellow.

15. You have to take a picture of a man with a camera, not with a wooden leg.

16. They were husband and wife.

17. He can't because he's dead.