1. Can a person have 'shiny eyes'? ('shiny' - bright, sparkling, for instance, with joy) I'd say someone's eyes were shining. I think it's possible to say "shining eyes", but "shiny eyes" does not sound right to me.
2. Do we sit IN or ON the back row (in the stalls, for example)? I'd say "in".
3. Is it okay to say "I better have a look at you' ? Does it mean the same as 'I'd better..." ? It should be "I'd better".
4. Is the word 'polyclinic' common? I found it neither in Macmillar nor in OLD. Should I say 'clinic' instead? It's given as "polyclinic" in COD. The word is not commonly used in the United Kingdom.