In English, when a vowel is followed by a single consonant and then another vowel, that indicates that the first vowel is a long vowel, as in for example the word kite, long i. If the consonant were double, then the vowel is short, as in the word kitten, short i. So, when adding a suffix, it is sometimes necessary to also add another consonant in order to avoid changing the pronunciation of the vowel that precedes it. Of course, as with all rules of English grammar, there are exceptions.
Yes it can.
I don't think so.
I don't think so.
when adding a prefix, the spelling of the root word doesn't change
Speakable does not have a prefix as it is written. Speakable does have a suffix, -able. A prefix can be added to speakable - unspeakable.
The prefix in "fearless" is "fear-" and the suffix is "-less."
Discount itself is not a prefix nor a suffix. There is no suffix in discount, but the prefix is dis-.
The prefix in "irreplaceable" is "ir-" and the suffix is "-able."
The prefix of vasoconstriction is "vaso-" and the suffix is "-constriction."
There is no prefix suffix for stem.
There is no prefix. The suffix is -ate.
Prefix: un- Suffix: -er