I have a speaking handheld electronic version of M-W's Collegiate Dictionary. It pronounces
opportunity as oppor-too-nity, not as opper-chu-nity which is a more common pronunciation as far as I know. Many other pronunciations I heard on my handheld dictionary sounded very weird and wrong to me at first but later they proved to be correct ones. The same problem is with pronunciations of words like
attitude and
prostitution. Locally the
-tu- unit in words like
opportunity,
attitude and
prostitution is pronounced somewhat like
chew.