The city of Qingdao has been working on building itself up as a city of sails ________ it successfully hosted the 2008 Olympics’ sailing program.

A．after

B．since

C．when

D．until

抹灰时待灰饼稍干后在上下灰饼之间用砂浆抹上一条宽10cm左右的垂直灰埂，此即为 ( )，作为抹灰厚度和赶平的标准。

A．标杆

B．标皮尺

C．标筋

D．长灰饼