2024年6月英语四级（第1套 · 含听力）选词填空

It's well known that physical exercise is beneficial not just to physical health but also to mental health. Yet whereas most countries have __26__, evidence-backed guidelines on the type and intensity of exercise __27__ for various physical health benefits, such guidelines do not yet exist for exercise and mood.
This is __28__ due to a lack of necessary evidence. However, a new systematic review brings us usefully up-to-date on the current findings in this area.
Before __29__ into some of the key take-aways, an important __30__ made in the review is between aerobic exercise and anaerobic. The former __31__ such things as walking, jogging and cycling and means exercising in such a way that your body is able to use oxygen to burn fat for energy. In contrast, anaerobic exercise—such as lifting heavy weights—is of such __32__ intensity that your body does not have time to use oxygen to create energy and so instead it breaks down glucose (葡萄糖) in your blood or muscles.
Beginning first with the influence of exercise intensity on the mood benefits of aerobic exercise, the researchers, led by John Chan at Shenzhen University, found __33__ results from 19 relevant studies. Some favoured higher intensity, others low, while seven studies found that intensity made no __34__ to mood benefits.
In relation to the intensity of anaerobic exercise, however, the results were far clearer— the optimum (最佳选择) for improving mood is __35__ intensity, perhaps because low intensity is too dull while high intensity is too unpleasant.