Mary felt________from the outside world，since she lacked an Internet connection and couldn’t receive any e­mail.

A．cut down　

B．cut in

C．cut off　

D．cut out

动脉导管未闭有显著肺动脉高压者出现发绀的部位是( )

A．全身
B．下半身
C．一侧肢体
D．上肢发绀较下肢发绀明显
E．右上肢发绀较左上肢发绀明显