5. many in high density residential areas ：是獨立分詞短語。注意它省略了being， 即 many (being) in high density residential areas. 此外，many 指的是 many transmitter towers.
6. at a rate more than three times that of adults 可以理解為 at a rate (that is ) more than three times that of adults， 意為“以比成人多兩倍的比率……”短語中的that 指代rate.倍數的表達法是：“數字 times 名詞/that”。如：
His salary is three times that of mine.
The sales volume of refrigerators in 2000 was two times that in 1999.
練習：
A. He says there is emerging evidence that children absorb low-level radiation at a rate more than three times that of adults6.
B. By the year 20004 it is estimated that Australia will have 8 million mobile phones： nearly one for every two people
C. “If mobile phones are found to be dangerous， they should carry a warning label until proper shields can be devised，” he said.
D. Then who finances the research?
E. For example， Telstra， Optus and Vodaphone build their towers where it is geographically suitable to them and disregard the need of the community.
F. The conclusion is that mobile phones brings more harm than benefit.
答案與題解：
1. C “空1”應該填入與low-level radiation 有關的內容，例如 low-level radiation 究竟有害還是無害。所以，C是合適的選項。此外，直接陰郁也佐證了選擇的合理性。
2. B “空2”前面一句介紹了澳大利亞擁有手機的現狀。選項B的內容是對到2000年年底之前手機發展前景的預測，內容連貫，是正確答案。
3. E 這一段的第一句說的是，許多微波發射塔建在人口稠密的居民區。選項E的內容涉及微波發射塔的地點選擇只考慮到地理位置，而不顧及公眾的需求。選項E擴展了第一句表達的信息。此外，選項E中出現 tower 這個詞，與第一句的 tower 相呼應，也佐證了選擇的合理性。
4． A “空4”前面一句說的是Robert Bell建議政府應該禁止在學校操場、兒童日托中心、醫院、運動場所以及兒童占比例較高的居住場所方圓500米范圍內建發射塔。選項A說明要這樣做的原因，因而是答案。
5. D “空5”后面一句說的是 major telephone companies 出錢資助研究項目的問題，提示了D是正確答案。