自考广告学要多久:疑难请教

The Environmental Protection Agency says jojoba oil is not a risk to non-target organisms. And it says it does not know of any harmful effects to humans even if the oil is eaten.
其中 not a risk non-target organisms 是何意,在句子中是什么意思?
**************************************************Many industrial uses for jojoba oil are being studied.这句话中"oil are being studied" 是正在进行时的被动语态吗? 该被动语态是修饰"jojoba oil"的吗?这句话是什么意思呢?
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Large plantings of jojoba in the United States are said to date back to the late nineteen seventies. 其中date back to是指 "从..时就有","追溯到" 但are said在句中是指什么意思?
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Many wanted to buy the rest of the supplies they would need before they began the trip into Canada。其中rest在句中是何意？
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望大家不吝赐教！
请大家帮我正确的翻译一下上面四个句子.