托福阅读句子插入题18

　　托福阅读中句子插入题是重要题型之一。根据托福阅读题型不同来进行专项练习，是短期提高托福阅读能力的有效方法。同学们需要多加练习哦!

　　托福阅读句子插入题：Minerals and Plants

　　【Paragraph 5】Scientists have known for some time that certain plants, called hyperaccumulators, can concentrate　minerals at levels a hundredfold or greater than normal. ■A survey of known hyperaccumulators identified that 75　percent of them amassed nickel, cobalt, copper, zinc, manganese, lead, and cadmium are other minerals of choice.　■Hyperaccumulators run the entire range of the plant world. ■They may be herbs, shrubs, or trees. ■Many members of　the mustard family, spurge family, legume family, and grass family are top hyperaccumulators. Many are found in tropical　and subtropical areas of the world, where accumulation of high concentrations of metals may afford some protection against plant-eating insects and microbial pathogens.(Minerals and Plants)

　　Look at the four squares [■] that indicate where the following sentence could be added to the passage.

　　Certain minerals are more likely to be accumulated in large quantities than others.

　　Where could the sentence best fit?