题目内容

动物致畸的三段试验的目的是

A. I段试验测试环境因素的对胚胎毒性和致畸性
B. Ⅱ段试验测试环境因素的对受孕率和生殖功能的影响
C. Ⅱ段试验测试环境因素对分娩后发育的影响
D. Ⅲ段试验测试环境因素对分娩后发育的影响
E. Ⅲ段试验测试环境因素对受孕率和生殖功能的影响

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有机硅树脂具有很好的耐水、防水性,但耐候性较差。

Why did they think $250 could be a reasonable price?

A. Because it was cheaper than the previous price
Because customers can divide them into several parts to eat
C. Because it was exactly the cost price
D. Because it was not the first time that the burger had been overcooked.

发泡聚氨酯是优质的防水涂料。

水体自净作用的概念是

A. 水污染后可通过水体自身的物理、化学、生物学作用,将污染物浓度逐渐降至污染前的状况
B. 水污染后可通过污水处理厂进行净化,使之达到污染前状况
C. 投入相应的净化剂,使污染物分解掉
D. 投入大量需氧菌,使污染物分解掉
E. 污水经综合利用后再排出

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