The data in a column of a web page that I have imported into Excel is
originally like this:

40-2
39+6
39
38-2

When the web page is imported, Excel interprets "40-2" and "38-2" as dates.
In fact they are not. So now the cell which contains "40-2" has "1940-02-01"
as data.

How can I stop Excel from interpret text such as "40-2" as dates? If I can't
do that, how can I get it back into its original format?