---You didn’t lock the back door.

一You are wrong．I         .

A．have locked it

B．lock it myself

C．did lock it

D．do lock it

常用于肝癌正电子发射计算机断层显像（PET）的显像剂是（）

A.¹¹C-CO₂

B.¹⁸F-FDG¹¹

C.¹⁸F-NaF

D.¹⁵O-H₂O

E.¹³N-尿素