(Notice the difference in the length of the vowel.)

4. Notice also that we have

[z]
in reservein research
diseasedisobey
dissolvedissolvent, dissolute
presumptionpresuppose

Find other examples (there are many). How do you pronounce disarm?

5. x represents [ks] in exercise, excellent, and in extra, exceed, express, extol, but [gz] in exert, examine, anxiety, exult, exonerate, exorbitant, exotic.

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Try to find a rule for the pronunciation of x.

In exile both pronunciations of x may be heard, [ks] being perhaps the more common.

For the dropping of h in compounds with ex- see § 47.