单选题   Shelly had prepared carefully for her biology examination so that she could be sure of passing it on her first ______.
 
【正确答案】 B
【答案解析】 考查名词同义辨析。句意：雪莱已为生物考试做了精心准备，以确保一次通过。intention意图，打算；attempt尝试，试图；purpose目的；desire渴望，愿望。