Mr. Black decided to give up his farm and devoted all his time to _____ those children living on the street.

[      ]

A. help

B. being helped

C. be helping

D. helping

最有诊断价值的辅助检查是

A．左膝CT
B．病理学检查
C．血培养
D．左膝穿刺抽液，生化检查及细菌培养
E．结核菌素试验