题目

Doctor often advises us to pay more attention to our diets and mental health and to take _____exami­nations. A. relevant    B. regular      C. adequate  D. accurate 答案：B一亿五千零三十万，写作 ，把它改写成用“万”作单位的数是 ，用“四舍五入”法取近似数约是 亿．