A.\(x = \frac{3}{{4\pi }}co{\rm{s}}\left( {\frac{{20\pi }}{3}t + \frac{\pi }{6}} \right)cm\)
B.\(x = \frac{3}{{8\pi }}co{\rm{s}}\left( {\frac{{20\pi }}{3} + \frac{\pi }{6}} \right)cm\)
C.\(x = \frac{3}{{4\pi }}co{\rm{s}}\left( {\frac{{20\pi }}{3}t - \frac{\pi }{6}} \right)cm\)  
D.\(x = \frac{3}{{8\pi }}co{\rm{s}}\left( {\frac{{20\pi }}{3} - \frac{\pi }{6}} \right)cm\)

A.\(\frac{{{I_M}}}{{{I_N}}} = {10^{{L_N} - {L_M}}}.\)   
B.\(\frac{{{I_M}}}{{{I_N}}} = {10^{\frac{{{L_N} - {L_M}}}{2}}}\)  
C.\(\frac{{{I_M}}}{{{I_N}}} = {10^{{L_M} - {L_N}}}.\)  
D.\(\frac{{{I_M}}}{{{I_N}}} = {10^{\frac{{{L_M} - {L_N}}}{2}}}\)

A.\(9m\)
B.\(16m\)  
C.\(6m\)
D.\(10m\)

A.92%
B.97,5%
C.86,4%
D.81,7%

A.volunteer
B.protection
C.conclusion
D.attention

A.don’t they
B.do they
C.does he
D.doesn’t he

A.presentable
B.rewarding
C.attractive
D.limited

A.presentable
B.rewarding
C.attractive
D.limited

A.eye
B.peek
C.flash
D.glimpse

A.bread
B.cheese
C.sandwich
D.egg