人字闸门是一种特殊形式的（）。
参考答案：平板闸门
.It was the practice _____ he got abroad _____ made him a good English speaker.
A．what; that
B．that; that
C．that; which
D．which; that
互感器加装膨胀器应选择（）的天气进行。（）
A、多云，湿度75%
B、晴天，湿度60%
C、阴天，湿度70%
D、雨天
