Additionally, for the sentence "Circula la respuesta que cree es apropiada", I honestly do not think that it is very well written, because it contains two verbs, "cree" and "es", but with only one conjunction, "que". If you really want to keep it in such structure, then it should be written as:
-- Circule la respuesta que cree que (la respuesta) es apropiada.
Other options: [Native speakers please kindly rectify any mistakes.]
-- Circule la respuesta que cree (la más) apropiada. = Circle the answer that you think (the most) appropriate.
-- Circule la respuesta apropiada según su opinión. = Circle the appropriate answer according to your opinion.
Please try to avoid unnecessary abbreviations, especially abbreviations that are generally used in local region, such as "CityU", which is though quite broadly used within Hong Kong, anyone who is in other countries possibly has no idea what it actually means. [For instance, a German might think that "CityU' could mean "Stadt-U-Bahn", i.e., the city subway!] Hence, if such abbreviation is necessary, then at least you should state the term in full when you first mention it.
Finally, I would recommend you the WordReference multilingual online dictionary, available at: www.wordreference.com , so that you may consult some translations of words in future. Additionally, you may also refer to the Google multilingual online translator, available at: translate.google.com , to get the first idea of some words or phrases.