通过哪些方式改造酶分子来满足实践需求？

牙齿的面可以描述为（）

A.牙冠有咀嚼功能的一面

B.牙冠发生接触的一面

C.上下颌牙齿在咬合时接触的部位

D.上下颌的后牙在咬合时发生接触的面

E.牙冠上有牙尖突起的部位

《中华人民共和国职业病防治法》规定，用人单位必须采用有效的职业病防护设施，并为劳动者提供个人使用的（）

A.职业病防护用品 

B.手套和工作服 

C.防护用品

语文课程应致力于学生（）的形成与发展。

Beijing: The United States and North Korea had their first ________in four months here this afternoon as part of the ________negotiations on how to end North Korea’’s nuclear program, but diplomats played down prospects for________.James A. Kelly, assistant________, and Kim Yong II, North Korea’’s deputy foreign minister, met ________of formal discussions, ________on direct dialogue that began after a stormy meeting ________in which North Korea warned that it was moving quickly to ________nuclear arms.The Bush administration had insisted ________that it would only hold talks with North Korea ________because, it argued, only ________pressure would persuade North Korea to________. It got its way when North Korea dropped its insistence on ________and agreed, after extensive efforts by China, to hold unusual simultaneous negotiations with ________,________,________and ________as well as the United States.Though Bush administration officials had not ________talking privately with the North Koreans during________, the fact that Mr. Kelly and Mr. Kim met on the first day was seen as a sign of ________by the American side.

襟翼位置指示器位于（）

A、P5后部

B、P1

C、P2

D、P3