小孩大便时出血是痔疮吗？

下图给出一棵二叉树，按照前序法周游二叉树的节点序列是

A．ABDEGCFHI

B．DGEBHIFCA

C．ADBGEFCIH

D．ADGEBHIFC

—What did he say just now?

—He asked me _____ in Kunming. [ ]

A. when did the meeting open

B. when the meeting opens

C. when the meeting opened

D. when does the meeting open

试论收养的法律特征和法律效力。

每个气藏都有含气外边界和含气内边界。

压风系统应具备哪些条件（）

A、专用风机

B、超温保护

C、安全阀

D、释压阀