OG详解-OG10 阅读 Q21

Choice A is the best answer because it most logically completes the text’s discussion of diaphragm contractions and hiccups. In this context, “involuntarily” means done without any control, or by reflex. The text explains that when a person’s diaphragm contracts and results in hiccups (which may be important for infants), those muscle contractions are “uncontrollable.” This context indicates that the diaphragm contractions occur without the person’s control.
Choice B is incorrect because the text indicates that researchers haven’t determined exactly why people hiccup, suggesting that it isn’t known that the uncontrollable muscle contractions generally occur “beneficially,” or with a good or helpful effect—even if one neuroscientist has found that it’s possible hiccups play an important positive role for a specific group of people (infants). Choice C is incorrect because the text describes the diaphragm contractions that result in hiccups as “uncontrollable,” or happening without the person’s control, so it wouldn’t make sense to describe them as occurring “strenuously,” or in a way that requires great effort or energy. Choice D is incorrect because nothing in the text indicates that the diaphragm contractions resulting in hiccups occur “smoothly,” or evenly and continuously. The text doesn’t describe the quality of the muscle contractions beyond stating that they are “uncontrollable.”