have加動(dòng)詞ed是什么時(shí)態(tài)

　　The two groups of children have quite different characteristics.

　　這兩組兒童具有截然不同的特點(diǎn)。

　　Now she won't have to go out to work any more.

　　現(xiàn)在她不必再出去工作了。

　　There have been many changes in recent years.

　　近幾年發(fā)生了許多變化。

　　Call me if you have any problems regarding your work.

　　你如果還有什么工作方面的問題就給我打電話。

　　No new SARS cases have been reported in the region.

　　該區(qū)沒有新增非典型肺炎病例。