如图,身高为1.6m的某学生想测量一棵大树的高度,她沿着树影BA由B到A走去,当走到C点时,她的影子顶端正好与树的影子顶端重合,测得BC=3.2m,CA=0.8m,则树的高度为____m.
定义a*b=a,a<bb,a≥b已知a=30.3,b=0.33,c=log30.3,则(a*b)*c=____ (结果用a,b,c表示).
The man doesn't have enough energy ____ (do) any exercise.