用力呼吸时吸气，呼气均伴有肌肉的收缩活动。
参考答案：对
(2013·安徽马鞍山两校模拟)—Which room would you prefer to live in, sir?
—________. As long as it is clean and comfortable.
A．I don't mind
B．I'm sure
C．No problem
D．Go ahead
