Only when he reached the teahouse　　　it was the same place he’d been in last year.

A．he realized

B．realized he

C．had he realized

D．did he realize

肌肉收缩滑行学说的直接证据是肌肉收缩时()

A．肌小节长度缩短 

B．暗带长度不变，明带和H带缩短 

C．暗带长度缩短，明带和H带不变 

D．相邻的Z线相互靠近 

E．明带和暗带的长度均缩短