多选题 Ellen Swallow Richards, a ______ environmental preservation in the United States, campaigned du ring the nineteenth century to ______ responsible practices in the discipline that has come to be known as ecology.

A、 foil for
B、 pioneer of
C、 mitigator of
D、 expose
E、 implement
F、 squelch

【正确答案】 B、E

【答案解析】[解析] ●逗号表示前后同义重复。
●第一空与has come to be known(被众所周知)同义重复。foil for……的阻力，pioneer of……的先锋，mitigator of……的缓和。答案选B。
●expose使受影响，implement实施，squelch压制/击溃。代入选项，答案选E。