—Lingling went to bed late yesterday, ______?

—Yes. She studied hard for the test.[ ]

A. wasn't he        

B. didn't he          

C. wasn't she      

D. didn't she

属于下颌骨外面的结构为

A．颏结节

B．上下颏棘

C．二腹肌窝

D．下颌舌骨肌线

E．舌下腺窝