多长时间尿细菌培养阴性，可报告无细菌生长（）

A.12h

B.18h

C.24h

D.36h

E.48h

Our son doesn't know what to__________at the university; he can't make up his mind about his future.[      ]

A. take in            　

B. take up          

C. take over      

D. take after