Choose the correct answer, A, B or C.

单选题 The student thought there were no crocodiles in Northern Africa because

A、 North Africa contains very little wildlife for the crocodile to prey on.
B、 she found no mention in the literature of their existence there.
C、 there is very little water in North Africa.

【正确答案】 B

【答案解析】解析：B本题听到“To start，I’d like to address a great question posed to me by a student duringyesterday’s office hours”这句话时再准备作答，因为这时才意味着正式开始。原文：there were no crocodiles in the Northern Region，and found no mention in the literature of theexistence of crocodiles in the North of Africa．所以B为正确选项。

单选题 Crocodiles live in groups of about

A、 20.
B、 38.
C、 46.

【正确答案】 A

【答案解析】解析：A本题C选项容易成为干扰，但那是Mauritania地区的数量，后面一句usual number a littleless than half that表明其实常规数量比46的一半还要少点。因此A为正确选项。

单选题 African crocodiles usually live in areas with

A、 hot, dry climates.
B、 hot, wet rainforests.
C、 warm, wet climates.

【正确答案】 C

【答案解析】解析：C原文表示气候的内容是：In general，crocodiles are more highly concentrated in wet，subtropical environments，sub-tropical为亚热带的意思，也就是暗指warm，wet climate。所以C为正确选项。

单选题 Crocodiles in dry areas live in caves located

A、 underground.
B、 in mountainsides.
C、 underwater.

【正确答案】 A

【答案解析】解析：A本题A为正确选项。原文说：Some African crocodiles have made dens by digging holes inthe ground…，就是live in caves located underground的意思，对A选项进行了解释。

单选题 What change caused changes in crocodile populations in North Africa?

A、 They were driven away by a fierce predator.
B、 Crocodiles evolved from desert creatures to wetland creatures.
C、 North Africa used to be wetland but slowly turned to desert over time.

【正确答案】 C

【答案解析】解析：C本题题干与原文相比变化不大，原文：Over time，though，the area dried out and the wetlandslowly turned to desert，leading the African crocodile to migrate south to the marshlands theycall home today．与C选项相呼应。