Apes don't ask questions
While apes can learn sign language and communicate using it, they have never attempted to learn new knowledge by asking a question. They don't realize that humans or other apes can know things they don't. It's a concept that separates mankind from apes.
In the 1970s there had been suggestions that apes are unable to ask questions and to give negative answers. According to studies, apes are able to answer human questions, and the vocabulary of the acculturated apes contains question words. Despite these abilities, apes are not able to ask questions themselves, and in human-primate conversations questions are asked by the humans only. Scientists designed a methodology to teach apes to ask questions by removing an important element from a familiar situation in the animal's world. Suppose a chimpanzee received its daily ration of food at a specific time and place, and then one day the food was not there. A chimpanzee trained in the interrogative might inquire "Where is my food?" , but this never happened during the tests.