"adalah" can also be removed in spoken language. prefix "ber-" from "berpikir will be missing, if it's used with comma (,). "berpikir" is intransitive verb (compared with "memikirkan" = to think about (transitive verb)). For examples : Aku pikir, dia tidak mengerti (I think, he/she doesn't understand) Aku pikir, dia mencoba menakutiku (I think, he/she tries to frighten me) or you can also verb "merasa" (literally means "to feel" (intransitive verb), but in this case you must remove prefix "mem" from "merasa", it becomes "rasa". For examples : Aku rasa, dia tidak mengerti (I think, he/she diesn't understand) Aku rasa, dia mencoba menakutiku (I think, he/she tries to frighten me) "kualitas paling penting" and "kualitas terpenting" are same. But "kualitas terpenting" is better used in order to make it short. bermain + mendukung makes no sense. In this case, it's better to use "bergaul" it sounds more natural. "memiliki rasa ingin tahu" means "to have curiosity". "bergaul" (intransitive verb), it is usually followed by preposition "dengan". but in your sentence, conjunction "dan" (and) has to be added in order to separate "bergaul" with another verb which followed it. "serta" means "and also".