检定一台Max=20t，e=20kg的电子衡器，已测得该衡器重复性为10kg，在标准砝码不足的情况下，采用其他恒定载荷来代替标准砝码，则以下说法正确的是（）.

A、至少应有1t的标准砝码

B、至少应有2t的标准砝码

C、至少应有4t的标准砝码

D、至少应有10t的标准砝码

Shipboard Oil Pollution Emergency Plans must be reviewed（）.

A.annually by the owner，with a letter submitted six months before expiration

B.only once every five years，with a letter submitted six months before expiration

C.and the entire plan resubmitted for approval once every five years，six months before expiration

D.annually by the owner，with a letter submitted to the Coast Guard within one month of the anniversary date of the plan approval