FIDIC合同条件下，签发( )必须由工程师亲自处理。
A．付款证书
B．工程接收证书
C．工程计量
D．履约证书
E．开工令
参考答案：A,B,D,E
Most of the teachers ______ to visit our school were young ones.
A．invited
B．to invite
C．being invited
D．had been invited
磁性次晶格
