Certain English words and expressions are commonly used also by speakers of other languages. Know-how is a term that can be heard in many business meetings, while comeback and come on are often used in sports. Similar to the case of no comment, see this post, there is often confusion about the correct English pronunciation. So, let’s take a closer look.
Know-how is pronounced just like the words know and how. The mistake often made is incorrect stress. In English, the stress is on the first syllable, hence [‘nəʊhaʊ] (British) or [‘noʊhaʊ] (American). Know-how is often but incorrectly stressed on the second syllable. Of course, when know and how are not joined together in the noun know-how, the stress may be on how instead of know, as in the example
Do you know how he got here?
You can listen to the correct pronunciation of know-how here. According to the Duden, in German, know-how can be stressed either on the first or the second syllable, see here. (For my German-speaking readers: did you know that the name Knoff-Hoff Show is also derived from know-how?)
Similarly, the noun comeback is also stressed on the first syllable, whereas in to come back the stress is typically on back. Again, the pronunciation is just the combination of come and back, [ˈkʌmbæk]. You can listen to it here. The German language has its own rule, with the Duden suggesting that comeback is pronounced as [kʌm’bæk], see here.
Finally, the phrase come on can often be heard when spectators cheer on athletes. For example, I remember hearing it quite a lot at climbing walls (climbers also like to use the French allez). The correct pronunciation of come on is to stress on, although most non-native speakers stress come instead, which is only correct for the noun come-on, see here.