— Who was your _______ English teacher? — She was Miss Li. A.the first B.first C.a first D. one 答案:B13.对于定义在[0,+∞)上的函数f(x),若函数y=f(x)-(ax+b)满足:①在区间[0,+∞)上单调递减;②存在常数p,使其值域为(0,p],则称函数g(x)=ax+b为f(x)的“渐近函数”(1)证明:函数g(x)=x+1是函数f(x)=$\frac{{x}^{2}+2x+3}{x+1}$,x∈[0,+∞)的渐近函数,并求此时实数p的值;(2)若函数f(x)=$\sqrt{{x}^{2}+1}$,x∈[0,+∞)的渐近函数是g(x)=ax,求实数a的值,并说明理由.