应是2sin(2π/3+φ)=2sin(2π/3+φ)=12π/3+φ=π/2+2kπ用代入法即可 把x=π/3 代入答案
y=2sin(2x+Ψ)当x=π/3时 y=2则 sin(2π/3+Ψ)=12π/3+Ψ=π/2Ψ=-π/6故 y=2sin(2x-π/6)选A
