Outside the exit, many fans waited for the great pop singer, _______to take a picture with him.

A．hoping

B．hope

C．hoped

D．to hope

一根钢管，已测得管的内直径为7.2mm；现用三角板和刻度尺量钢管的外径，如图所示。由此得钢管外径是_________cm，钢管壁的厚度是__________mm。