某小儿在幼儿园接触过处于卡他期的百日咳患儿，此时应对该健康小儿观察（）
A.28天
B.21天
C.14天
D.7天
E.3天
参考答案：B
If a seller finds any discrepancies in the letter of credit against the sales contract, whom should he write to asking for an amendment（）
A．the issuing bank
B．the advising bank
C．the applicant
D．the negotiating bank
出口地交货条件下的贸易术语有（）
A.FCA
B.DES
C.CIF
D.CPT
E.DDP
