A.2sin45° B.π*R2 C.x÷y×5 D.(x+1)/(x^2+1)/2
A.雙引號(hào) B.單引號(hào) C.方括號(hào) D.花括號(hào)
A."A">"a" B."9">"a" C."That">"Thank" D.12>12.1