流量孔板的取出口（）伸入管道内。
A、必须
B、不能
C、伸不伸入都行
参考答案：B
About __________ of the books in our school library are written in Chinese.[ ]
A. four-fifth
B. four-fifths
C. fourth-fifths
D. fourths-fifth
福建土楼的特色是什么？
