China's badminton superstar Lin Dan won a thrilling final for his fifth world champion in Guangzhou on Sunday over Lee Chong Wei, who ______ his game due to injury.

A．concerned

B．recovered

C．abandoned

D．recognized

在切削过程中，工件上存在三个表面（）。

A.粗表面

B.待加工表面

C.在加工表面

D.已加工表面