自发性气胸包括（）
A.继发性自发性气胸
B.张力性自发性气胸
C.闭合性自发性气胸
D.开放性自发性气胸
E.原发性自发性气胸
参考答案：B, C, D
简述利益群体的相互关系。
A 3G mobile phone, _____ to be most useful and fashionable, is popular with some teenagers.[ ]
A. consider
B. considering
C. considered
D. to be considered
