组合式抽油杆打捞筒的上简体其上部有螺纹与上接头连接，其下部有（）。
A.弹簧座
B.卡瓦
C.一段外锥面
D.一段内锥面
参考答案：D
—I want to return the book to Jack, but I can't find him.
—He _____ the library. You can find him there. [ ]
A. has been to
B. has gone to
C. has left
D. went to
出租汽车拒载、中途甩客和倒客的计（）分。
A、5
B、10
C、20
