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。