Here's why:
* Phonetic Simplification: English speakers often simplify pronunciations for ease of speech. In these words, the "b" sound is followed by an "m" sound, making it easier to just say "m" without the "b".
* Historical Changes: Over time, the pronunciation of words can change. It's likely that the "b" in these words was originally pronounced, but gradually faded out.
It's interesting to note that this doesn't apply to all words with "mb" combinations. For example, you would still pronounce "bomb" with the "b" sound.
So, yes, you are correct! It's perfectly natural to pronounce "combing", "bombing", and "climbing" without the "b".