职业病是指人们在生产劳动过程中，因作业环境中（）所致的特有性疾病.

阅读理解。

     Once upon a time, there was a farmer. He didn't have a lot of money, so he used an old horse

to plow(耕)his field instead of a tractor(拖拉机).

     One afternoon, while working in the field, the horse died. Everyone in the village said, "Oh, what

a terrible thing!" The farmer just said, "We'll see." He was such a good person that the villagers got

together and bought him a new horse as a gift.

     Then many people said, "What a lucky man!" And the farmer replied, "We'll see." 

     A few days later, the new horse jumped over the wall and ran away. Everyone in the village said,

"What a poor man!" 

     The farmer smiled and said. "We'11 see." But finally, the horse found his way home, and everyone

said, "What a fortunate man!" The farmer said, "We'll see."

     Later in the year, the farmer's young boy went out, riding on the horse. He fell off the horse and

broke his leg. Everyone in the village said, "What a poor boy!" The farmer said, "We'll see." 

     Two days later, the army came into the village to ask people to be soldiers. When they saw that

the farmer's son had a broken leg, they decided not to ask him to join the army.

     Everyone said, "What a lucky young man!" The farmer smiled again and said, "We'll see."

1. The farmer used a horse to plow the field because _____.

A. the horse was his best friend

B. the horse was very young and strong

C. he was too poor to afford a tractor

D. the field was only suitable for horses 

2. After the horse died, the farmer was _____ when he heard the villagers' words. 

A. happy

B. calm

C. afraid

D. angry 

3. When the farmer's new horse ran away, the villagers _____.

A. gave the farmer another horse

B. liked the farmer's attitude (态度)

C. hated the farmer

D. felt sorry about it  

4. From the passage we learn that _____.

A. we should do things when we can

B. we should be sad when we are in trouble

C. we should not believe what other people say

D. if we are positive, all situations (境遇) are gifts

某病人既往有胆结石病史，突然出现身目染黄，右胁疼痛，牵引肩背，恶寒发热，大便色淡灰白。治疗当用 （）

A.小柴胡汤

B.大柴胡汤

C.柴芩温胆汤

D.黄连温胆汤

E.茵陈蒿汤

裸子植物是种子植物中较低级的一类，它们的胚珠外面没有子房壁包被，不形成果皮，种子是裸露的，故称裸子植物。下列植物中不属于裸子植物的有( )。

A．苏铁

B．银杏

C．核桃

D．云杉

水硬性胶凝材料是一种和水成浆后既能在（）硬化，又能在（）中硬化的胶凝物质。

如图所示，物块A的质量m＝2 kg（可看着质点）；木板B的质量M＝3 kg、长L＝1 m。开始时两物体均静止，且A在B最右端，现用F＝24 N的水平拉力拉着轻质滑轮水平向左运动，经过一段时间，物块A滑到木板最左端，不计一切摩擦，求：

(1)此时物块A的速度.

(2)这个过程中拉力F做的功.