Rather than ________ abroad with her parents, she preferred __________ volunteer work during the holiday.

A．to travel; to do

B．travelling; doing

C．travel; to do

D．to travel; doing

¹³¹I治疗甲状腺疾病时，主要利用其发射的：()

A．X射线

B．α射线

C．β射线

D．γ射线E

E．俄歇电子