A、 Branches.
B、 Leaves.
C、 Grass.
D、 Flowers.

【正确答案】 D

【答案解析】解析：细节题。从These camps were just groups of simple houses that were made of branches and leaves orgrass．可知古时人们用树枝、树叶和草扎营，所以排除的D即为答案。

A、 Because they wanted to find more food.
B、 Because they wanted to build new camps.
C、 Because they wanted to escape enemies.
D、 Because they wanted to find new spices.

【正确答案】 A

【答案解析】解析：细节题。从After a few weeks they moved to another place in order to find more food there．可知在古代人们从一个地方迁徙到另一个地方是为了寻找更多的食物，所以答案为A。

A、 Life is a lot easier.
B、 There are fewer dangers.
C、 Most people do not have to hunt for food.
D、 There is more excitement.

【正确答案】 D

【答案解析】解析：细节题。由Life is a lot easier than it was in the old days．和There are fewer dangers，but there is less ex-citement．以及Most people do not have to hunt for food…可知较之过去，现代生活更加轻松，危险更少，无需狩猎，排除的D是对原文的反义叙述。

A、 Because they try to find some excitement.
B、 Because they try to have fun from hunting.
C、 Because they try to get back to nature.
D、 Because they try to look for adventure.

【正确答案】 C

【答案解析】解析：细节题。由A lot of them go camping in the country，or by the sea．They try to get back to nature．可知现代人们露营源自于回归自然的渴望。所以答案为C。