— When can I come for the photos? I need them tomorrow afternoon.

— They ____ be ready by 12:00. [ ]

A. can

B. should

C. might

D. need

重金属

A．在盐酸酸性条件下检查
B．在硝酸酸性条件下检查
C．在醋酸盐缓冲液(pH3.5)中检查
D．在硫酸酸性条件下检查
E．在磷酸盐缓冲液(pH6.8)中检查
以下杂质检查的条件是