—Is it his left kidney (肾) ______ Tian Shiguo donated (捐献) to his mother — Yes. The kidney saved his mother and is expected to extend her life for 15 years.

A．Self-respect competition helps to boost.
B．The different opinions people have about competition.
C．The harmful competition does to personal quality development.
D．The necessary experience of failure in competition.

A．It pushes society forward.
B．It builds up a sense of duty.
C．It improves personal abilities.
D．It encourages individual efforts.