单项选择题
Care should be taken to decrease the length of time that one is ______ loud continuous noise.
单项选择题 It is not easy to learn English well, but if you ______, you will succeed in the end.
单项选择题 My cousin likes eating very much, but he isn't very ______ about the food he eats.
单项选择题 Cancer is second only ______ heart disease as a cause of death.
