In order to know how heavy the elephant was, he wrote down the weight of each stone and then           ____all the weights.

A．packed up

B．added up

C．went through

D．set down

商业银行贷款按其信贷资金的来源可划分为( )。

A．可疑贷款

B．关注贷款

C．自营贷款

D．委托贷款

E．次级贷款