How do you speak assault?
Is a pronounced A or uh?
There are two ways to say ‘a’ when it is used as an indefinite article, these two pronunciations are: “aye” (/eɪ/) or “uh” (/ə/). Both pronunciations are correct and it is really a matter of personal preference which one you use.
Is the T silent in exactly?
In practice, yes it is virtually silent unless one makes a special effort to pronounce it. When we have a consonant cluster here /ktl/ one sound is often not heard. The linguistice term for it is “dissimilation”.