Here, Haydee. I'm sure this will clear it right up for you...
"Since sure, and sugar begin with s-, the assimilation with the palatal on-glide of the (original) "long u" is (historically) complete, and the syllable-final consonant "shortens" the remaining -u- sound. In words like 'visual' and 'tissue', if the syllable boundary I(low energy point) falls before the on-gline, the apical (tongue tip) fricative may not be palatalized (or may be only partially palatalized). If the fricative is fully palatalized, there is much less likely to be a hint of the yod on-glide."
See?
Wendy
"Since sure, and sugar begin with s-, the assimilation with the palatal on-glide of the (original) "long u" is (historically) complete, and the syllable-final consonant "shortens" the remaining -u- sound. In words like 'visual' and 'tissue', if the syllable boundary I(low energy point) falls before the on-gline, the apical (tongue tip) fricative may not be palatalized (or may be only partially palatalized). If the fricative is fully palatalized, there is much less likely to be a hint of the yod on-glide."
See?
Wendy