about后面加什么

　　It's about this high.

　　大約有這么高。

　　There was much discussion about the reasons for the failure.

　　就失敗的原因進行了大量的討論。

　　The population is increasing at about 6% per year.

　　人口以每年約6%的速度增加。

　　It's only human nature to be worried about change.

　　對變革有憂慮不過是人之常情。

　　We estimated it would cost about  5 000.

　　我們估計要花費大約5000歐元。