They have been working on the perfection of the new model.

　　他們一直在努力完善新型號。

　　None of this would have been possible without their help.

　　如果沒有他們的協助，這事沒有一樣能辦成。

　　What books have been set for the English course?

　　英語課布置要用哪些書？

　　The plans have been under discussion for a year now.

　　這些計劃至今已討論一年了。

　　No new SARS cases have been reported in the region.

　　該區沒有新增非典型肺炎病例。