thE russiAn oFFiCiAl's visit to ChinA Aims At______.
A．strEngthEning sECurity CoopErAtion
B．ExpAnDing into CEntrAl AnD EAstErn EuropE
C．DisCussing BorDEr issuEs
D．rEAChing A BilAtErAl AgrEEmEnt in EConomy