（）是一种自动排泄蒸汽管道的凝结水，并能阻止蒸汽流出的阀件。
A、减压阀
B、疏水器
C、溢流阀
D、蝶阀
参考答案：B
Passage 1
When did I decide to find out about "Aunt Maggie" a. Three years ago. b. When my father died. c. About 85 years after my correspondence with her. d. When i was nineteen.
皮亚杰将儿童的认知发展分为（）；（）；（）和形成期四个阶段。
