A.society
B.social
C.socialize
D.sociable

A.communication
B.instance
C.attention
D.signal

A.small
B.rude
C.slight
D.formal

A.clapped
B.nodded
C.shook
D.hold

A.head
B.hand
C.eye
D.ear

A.coming nearer to
B.catching sight of
C.pointing at
D.looking up to

A.on
B.to
C.at
D.for

A.greeted
B.thanked
C.congratulated
D.agreed

A.\(\frac{R}{{\sqrt {{R^2} + Z_C^2} }}\)
B.\(\frac{{\sqrt {{R^2} + Z_C^2} }}{R}\)  
C.\(\frac{{\sqrt {\left| {{R^2} - Z_C^2} \right|} }}{R}\)  
D.\(\frac{R}{{\sqrt {\left| {{R^2} - Z_C^2} \right|} }}\)

A.Mĩ.
B.Pháp.
C.Anh.
D.Liên Xô.