Lizards, 33 can change the color of their skin and 34 the trees and leaves around them. 35 , they cannot be detected by other animals that threaten them.
答案：(B) for instance
插入語 for instance（例如）舉例，作為解釋前文「其他動物形式」的具體例子（蜥蜴）；however（然而）、in case（以防）、more or less（或多或少）都不符合這裡舉例的語意。
本題大考中心未公布逐題答對率，以下不談數據，只談觀念。
however 在這裡有一點誘惑力，因為插在主詞與動詞之間的轉承語，最常見的確實是 however。但位置只告訴你「這裡要放一個轉承語」，放哪一個還是得看前後兩句的關係。
四個選項都是插在主詞後面的轉承語，可見這一格考的是這一句與前一句的關係。前一句是一句通則：We have learned much about survival from lower forms of animal life.（我們從低等生物身上學到很多關於生存的事。）本句是 Lizards, ___ , can change the color of their skin ...（蜥蜴，……，能改變膚色……）——蜥蜴正是「低等生物」的一個具體例子。從通則走到一個具體個案，這就是舉例，填 for instance（例如）。這一條線在題庫裡反覆出現：89 年第 27 題與第 29 題、88 年第 25 題考的都是「後面這一句究竟是在重述、在舉例，還是在推進」。只要看出前一句是通則、這一句是個案，就填舉例的轉承語。
however（然而）：轉折，但前後兩句是通則與例子的關係，同向。in case（以防、萬一）：帶出預防性的條件，後面要接子句。more or less（或多或少）：講程度的模糊，與舉例無關。
for instance（例如）、for example（舉例來說）、such as（例如，接名詞）、change color（變色）、more or less（或多或少）、in case（以防萬一）。
All forms of life have an instinctive urge to survive. Nature provides 31 with the means of survival. We have learned much about survival from 32 forms of animal life.
Lizards, 33 can change the color of their skin and 34 the trees and leaves around them. 35 , they cannot be detected by other animals that threaten them. Nature provides other forms of protection 36 environmental dangers.
Human beings, too, 37 special devices to protect 38 . Their skin is very 39 to temperature changes. 40 warm weather, sweating helps humans regulate their body temperature.