食管在静止状态时，管腔呈：（）
A．扩张
B．塌陷
C．下端开放
D．上端开放
E．收缩
参考答案：B
She is a _____ girl. It means she is ______. [ ]
A. 16 years old; 16-year-old
B. 16-year-old; 16-year-old
C. 16 years old; 16 years old
D. 16-year-old; 16 years old
煤炭气化技术分为（）和地下煤气化技术两种。
