第21题: [单项选择]Questions 19 to 21 are based on the conversation you have just heard. A. Bending the elbows as low as possible. B. Keeping the body straight. C. Bending the body at the waist. D. Keeping the feet to the floor. 参考答案:B 答案解析:[听力原文] What is the most important thing in doing push-ups