选择自动地把外来较高压力的介质降低到需要压力的阀门（）
A、针形阀
B、止回阀
C、安全阀
D、减压阀
参考答案：D
从A、B、C、D四个选项中选出与所给句子划线部分意思相同或相近并能替代的的那一项。
— Who went to school early last term?
— Meimei used to be the first one. [ ]
A. got used to being
B. was used to being
C. was often
D. was used
液体汽化有两种方式：______和______．我国新疆的吐鲁番地区修建庞大的地下灌溉工程--坎儿井，就是减少输送过程中的水的______．
