I am always        to speak in the front of the classroom.[ ]

A. disappointing                  

B. scared

C. surprised                      

D. nervous

儿童吮指习惯的诊断性标志是（）

A．牙弓狭窄

B．上颌前突

C．开唇露齿

D．后牙反

E．手指上有胼胝