题目选项分析

Unlike amateur clammers, who usually dig clams by hand during the summer, professional clammers work year-round, using all-weather instruments such as the dredge or a 20-foot-long implement known as a bull rake.

Unlike amateur clammers, who usually dig clams by hand during the summer, professional clammers working year-round and using such all-weather instruments as a hydraulic dredge or a 20-foot-long implement known as a bull rake.