Perhaps you should try some spelling variations:
"varying environments and operational definition" » "learning environments and operational definition", "working environments and operational definition", "changing environments and operational definition", "making environments and operational definition", "marketing environments and operational definition"
"varying environments and operating conditions" » "learning environments and operating conditions", "working environments and operating conditions", "changing environments and operating conditions", "varying environments and loading conditions", "making environments and operating conditions", "marketing environments and operating conditions"
"varying environment and operational definition" » "learning environment and operational definition", "making environment and operational definition", "marketing environment and operational definition"

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