跨肺压是指()
A.肺内压与大气压之差
B.肺内压与胸膜腔内压之差
C.大气压与胸膜腔内压之差
D.大气压与胸廓回缩力之差
E.大气压与肺回缩力之差
参考答案:B
Li Ming __________ Christmas card now.[ ]
A. write
B. is writing
C. is writeing