—How many       are there in your school?

— Twenty. 

A. woman teachers           B. woman teacher          C. women teachers

纵隔肿瘤的临床表现有

A．咳嗽、呼吸困难、发绀

B．吞咽困难

C．肋间神经痛

D．霍纳综合征

E．上肢疼痛麻木