• have, having
• love, loving
• make, making
• take, taking
• give, giving
• hate, hating
• strive, striving

Etc. When a verb in its lemmatic form ends with "-e" then its present participle omits that letter.

Except that the British make an exception of the word "age" and write "ageing".

Are there other such exceptions? Are there any such exceptions in American usage?