In addition to the above replies, if you are referring to infallibly defined teachings, you absolutely must accept them if you are to be a Catholic. This is based on reason and also on what the previous posters were saying.
You have questions about certain teachings? Certainly you need to investigate. However, not understanding (a difficulty in understanding) is not equivalent to not believing (doubt that the teaching is true.) Like the previous posters, I have done so and this reaffirmed my belief that Catholicism is correct. Therefore, when I have difficulty understanding a particular teaching (e.g., exactly how can there be three persons in one being where none are the other, yet none are finite.), I don’t doubt the truth of it. Why? Because of how much I have questioned in the past. Time and time again the Catholic Church has clearly demonstrated that her teachings are correct. Catholicism is the only religion I have encountered that is completely consistent and has never changed even one claimed doctrine in its entire existence. I also realize that my inability to understand a concept doesn’t mean that concept is wrong. Even the Church doesn’t claim to fully understand the Trinity. It is referred to as a Mystery - something beyond the finite limits of human understanding. However, it has been revealed and is true, therefore I must accept it. One can have innumerable difficulties with understanding and not have doubt.
Another issue of acceptance is that of defining who you are. I am a Catholic. That means that I accept all of the teachings of the Church. If I knowningly reject Catholic doctrine, then I cease to be a Catholic. Therefore, there is truly no such thing as a pro-choice Catholic (except for those who somehow haven’t learned the Church’s teaching concerning abortion). Catholicism is a system of beliefs and a way of life. Any time there is a known conflict, you are faced with a choice: Are you Catholic or not? Archbishop Bruskewitz (spelling?) once said that the real difference between a Protestant and a dissenting Catholic is that the Protestant has more integrity. What he meant is that a Protestant, recognizing that he rejects Catholic doctrine, doesn’t call himself a Catholic. The dissenting Catholic somehow believes that he can be a Catholic, even a “good” Catholic, while rejecting Church doctrine.
Therefore, you can question your beliefs. Your answers will define who and what you are. If you knowingly reject Catholic teaching, you cease to be a Catholic; whether or not there is any formal declaration concerning the matter. It’s as simple as that.