问题 选择题

被称为“第七类营养素”的物质是(   )

A.维生素

B.无机盐

C.膳食纤维

D.水

答案

答案:C

题目分析:膳食纤维是一种不能被人体消化的碳水化合物,分为非水溶性和水溶性纤维两大类,纤维素、半纤维素和木质素是三种常见的非水溶性纤维,存在于植物细胞壁中,而果胶和树胶等属于水溶性纤维,则存在于自然界的非纤维性物质中,营养学家将膳食纤维放在碳水化合物、蛋白质、脂肪、维生素、无机盐以及微量元素等人体六大营养素的队伍里,并称它为“第七营养素”,故选C。

阅读理解

It's very early in the morning and I'm sitting outside. It's also very cold and dark. With me is Jim Nightingale, and he is the reason I'm up so early. He passes me a hot cup of coffee. "Not long to wait now," he says. I hope he's right.

After a few minutes there is a very weak light in the east, and then I hear a bird singing. It sings very loud and very clear. "That's the robin(知更鸟)," says Jim. A few more birds start singing with the robin and Jim knows the names of them too. Half an hour later, there are more and more birds singing, and it's very loud! Suddenly, all around us the air is full of the sound of birdsong. This is the dawn chorus(晨鸣), and it's beautiful.

"Wow, this is amazing!" I tell Jim, who is smiling. "Is there a dawn chorus every morning?"

"Birds can sing any time of the year but the best time is the end of winter and during the spring. This is when the birds sing most."

"Really? So, why do they sing?" I ask.

"Well, there are two reasons," explains Jim. "Most of the songbirds who sing are males. They want to find a female(雌性)so they sing to show how strong they are. The females listen and choose the best singer! The birds also sing to tell other males to go away. They need their own area; they don't like sharing with another male."

I listen to the birds; the songs seem too much to me. "Do the birds sing a special song in the morning?"

"That's a good question," replied Jim. "The successful birds have many kinds of calls and songs. Sometimes they copy the songs of other birds. This makes it sound like there are many birds in that place already and other males stay away. Also the female likes songs with different notes. Some birds, for example the European wren, have songs that contain over 700 different notes per minute!"

So, how does Jim know so much about birds? Well, he works as a volunteer for the Royal Society for the Protection of Birds. He is trying to help the birds live in the modern world. "More and more of the birds' habitat disappears every year. The sparrow, for example, was a very common bird in the UK, now it's in danger."

By now the sun is up and the birds are quiet. It's light so they can start looking for food, they need a big breakfast after all that singing.

小题1:Why does the writer get up early in the morning?

A.To visit her friend.

B.To drink hot coffee.

C.To see different birds.

D.To hear birds sing.小题2:A bird sings early in the morning mainly_______.

A.to call a female's attention

B.to fight with other males

C.to find a place to live in

D.to start looking for food小题3: According to the text, which of the following statements is true?

A.At first the writer is happy to be up so early in the morning.

B.Male birds have their own ways of fooling other birds.

C.It's easier for the birds to find food early in the morning.

D.Jim has a job with the Royal Society for the Proteciton of Birds.小题4:The text is mainly about_______.

A.the robin's songs

B.the birds' habitat

C.why birds sing

D.how to protect birds

单项选择题