And, as weed expert Bill Curran at Penn State University points out, they avoid the use of chemicals. Or the labor of pulling weeds by hand.

就像宾夕法尼亚州立大学的杂草专家指出的，weed whackers割草机避免了化学品的使用，也避免了手工清除杂草的劳动。

youdao

Bill Curran is a professor of weed science at Penn State.

Bill Curran是宾夕法尼亚州立大学的杂草科学教授。

youdao

Bill Curran at Penn State in University Park,Pennsylvania, is a professor of weed science.

VOA: special.2010.08.10

Bill Curran is a professor of weed science at Penn State,in University Park,Pennsylvania.

VOA: special.2009.05.26

The fans, who belted out support for Bill O'Brien, Penn State's new head football coach, numbered in the hundreds, CNN affiliate broadcaster WGAL said.

CNN: Penn State football loses star tailback to USC

Last week in Arizona, the Browns interviewed Cardinals defensive coordinator Ray Horton, Oregon coach Chip Kelly, Syracuse's Doug Marrone and Penn State's Bill O'Brien.

NPR: AP Sources: Browns Meet 2nd Time With Whisenhunt

Penn State has since hired New England Patriots offensive coordinator Bill O'Brien as head coach.

WSJ: Joe Paterno Dies At 85 From Lung Cancer Complications