Rick Howells is the arborist (树木栽培家) for the Shade Tree Commission in Allentown, Pennsylvania. He manages the care of all of the trees in the city,     1    (include) the trees that line the streets.

Trees can make a city prettier, sure. But that’s not    2    (they) only advantage, Howells explained. Trees can save lives by absorbing (吸收)    3    (pollute) from cars and   factories. Trees can also help slow climate change by absorbing carbon dioxide, one of the main    4    (cause) of climate change. In cities, trees provide a home    5    birds and bees. They also offer a calming effect on the community. That is one reason why there    6    (be) less crime in tree-lined areas.

“Trees must be trimmed (修剪) and, if they are diseased, cut down so that they don’t become a risk to the community. It isn’t     7    easy task,” Howells said. “You have to know types of knots (结) for the ropes and    8    (difference) kinds of rigging (索具).” Rigging equipment is tied to trees so that they can be trimmed and cut    9    (safe).

To Howells, taking care of trees isn’t just a job. It’s also a hobby. He loves trees and    10     they bring to a community. “If you take good care of a tree,” he said, “everything around it becomes beautiful, too.”