The sentence in the subject line is one of the four choices given in Question #1 of the the first mini-test of HTSK - the objective is identify the one and only one sentence with correct particle usage. While I can see that choice #4 (나는 병원 옆에 있어) is correct, I don't understand why 저는 펜을 있어요 is incorrect (according to the answer key at the bottom of the page). Please help me understand.
'을' is an object particle(목적격/대격 조사). In that case, '펜' should be an object, and we need a transitive verb. In the sentence '있다' seems to have the meaning 'to have', but lexically it just means 'to exist' or 'to be'. Thus '있다' does not require an object. the correct sentence should be either 저는 펜을 가지고 있어요 or 저는 펜이 있어요