Though ___________ to see us, the professor gave us a warm welcome.

A．surprising

B．was surprised

C．surprised

D．being surprised

关于X线的叙述，错误的是

A．X线是一种电磁波
B．X线波长，穿透力弱
C．L层比M层产生的X线波长长
D．L层比M层产生的X线波长短
E．X线波长与电子所在壳层有关