211. be on duty 值班, 值日, 在上班时　­

210. go on duty 上班　­

209. come off duty 下班　­

208. be due to 是由于　­

207. in doubt(=in a condition of uncertainty)对…表示疑惑　­

206. without doubt (=undoubtedly)无可置疑地　­

205. have…to do with 与…有关系　­

204. do away with(=get rid of; abolish; discard eliminate) 除去,废除,取消; do away with (=kill) 杀掉, 镇压　­

203. distinguish…from 把…与…区别开　­

202. distinguish between (=make or recognize differences) 辨别　­