My friend ______ from the UK. She studied at Oxford for four years, during which we communicated with each other on the Internet.

A．stepped

B．has returned

C．went

D．has learned

建筑工程监理代表建设单位主要监督承包单位的（）等。

A.项目管理水平

B.施工质量

C.建设工期

D.企业组织结构

E.建设资金使用