Everything in the natural world works effectively (有效地). Take a look at woodpeckers, for example, and you’ll understand.

A woodpecker taps (轻叩) its head against wood nearly 12,000 times a day. Doing something like that all day long must hurt! Think of how you would feel if you hit your head against something ______ 1 ______ only once.

However, in nature, everything happens for a reason. Woodpeckers have long, sharp beaks which they use to make holes in trees to ______2 ______ tasty insects inside. Their special toes allow them to hold on tightly (紧紧地) as they bang their heads against trees. They also have a strong tail feather, which they use to keep their balance while they ______ 3 ______.

But how do woodpeckers ______ 4 ______ brain injuries (伤害)? One of the most interesting things about woodpeckers is their tongue. It is very long—sometimes twice as long as the bird itself. The woodpecker can wrap (包) its long tongue ______ 5 ______ its brain inside its head. Each time the bird hits a tree with its head, its tongue protects its brain from injury.

That’s ______ 6 ______ a woodpecker can tap all day long and not get a headache.

1.1.

A thick

B smooth

C hard

D

解析：选C。C.空格前提到 “用头撞击某物”，结合常识，啄木鸟撞击的木头是坚硬的，且此句是类比啄木鸟的啄木行为。thick（厚的）、smooth（光滑的）均不符合语境，hard（坚硬的）契合逻辑，故选 C。

2.2.

A smell

B watch

C find

D

解析：选C。C.句意：啄木鸟用喙在树上凿洞，目的是______树里美味的昆虫。smell（闻）、watch（观看）不符合 “凿洞” 的目的，find（寻找、找到）能准确表达啄木鸟啄木找虫的行为，故选 C。

3.3.

A sleep

B work

C fly

D

解析：选B。B.前文描述啄木鸟啄木凿洞、用尾羽保持身体状态的场景，这是它的觅食工作过程。sleep（睡觉）、fly（飞翔）与语境无关，work（工作、劳作）能指代啄木鸟的啄木行为，故选 B。

4.4.

A get

B avoid

C protect

D

解析：选B。B .后文提到啄木鸟的舌头会保护大脑免受损伤，由此可知本句是问啄木鸟如何 “避免” 脑部受伤。get（得到）不符合语境；protect（保护）用法多为 “protect sth. from...”，后接宾语为被保护的对象，此处宾语是 “brain injuries”（脑部损伤），用avoid（避免）更符合语法和语义，故选 B。

5.5.

A around

B along

C above

D

解析：选A。A.句意：啄木鸟能将长长的舌头在头骨内缠绕住大脑。wrap around是固定搭配，意为 “缠绕、包裹”；along（沿着）、above（在…… 上方）无法表达 “缠绕” 的动作，故选 A。

6.6.

A why

B when

C where

D

解析：选A。A.前文详细解释了啄木鸟舌头保护大脑的原理，本句是总结 “这就是啄木鸟整日啄木却不头痛的原因”。That’s why... 是固定句式，用于解释原因；when（何时）、where（何地）不符合语境，故选 A。