At the age of 29, Dave was a worker, ________ in a small apartment near Boston and ________ what to do about his future. (2009湖南卷)

A．living; wondering

B．lived; wondering

C．lived; wondered

D．living; wondered

尤文肉瘤主要成分来源是

A．成骨细胞
B．成纤维细胞
C．成软骨细胞
D．骨髓细胞
E．破骨细胞