重点讲解：
1. clean up
清理，清除；
eg. The mayor is determined to clean up the city.
市长决心清除市内的不良现象mf=*|HLii5。
eg. They fought bravely to clean up the bandits.
他们英勇作战以肃清土匪]wW[],~RT~)F2*+U。
2. participate in
参与；参加；
eg. I am too clumsy of speech to participate in the debate.
我太笨嘴拙舌了，参加不了辩论会Mr^uZ-)Vv8s+amr;sPj。
eg. He tamed the urge to participate in the new venture.
他抑制住想参加新的冒险的冲动G(,,Z)ARNM+4+。
3. for the first time
初次；首次；
eg. He felt for the first time a stabof fear.
他第一次感到了一阵恐怖z%b1Gn!0J~k.7。
eg. I went to the tropics for the first time last year.
我去年第一次去了热带地区8M0pG~gUuH+mP#Tj。