差压变送器无输出信号，则下列故障判断中不正确的是（）。
（A）无气源
（B）恒节流孔堵塞
（C）挡板离喷嘴太远
（D）平衡阀未关
参考答案：D
As big cities are ____ rapidly, it's time for us to move our attention to small and medium-sized cities and
even towns. [ ]
A. circulating
B. campaigning
C. exporting
D. expanding
Jack is _________years old. Today is his _________ birthday.
A．sixteenth; sixteen
B．sixteen; sixteen
C．sixteen; sixteenth
D．sixteenth; sixteenth
