下列关于分式方程增根的说法正确的是( ) A.使所有的分母的值都为零的解是增根

题型:选择题

问题:

下列关于分式方程增根的说法正确的是(  )

A.使所有的分母的值都为零的解是增根

B.分式方程的解为零就是增根

C.使分子的值为零的解就是增根

D.使最简公分母的值为零的解是增根

考点:解分式方程
题型:选择题

如右图所示,容器A(容积2 L)中有1×105 Pa的空气。在容器B(容积1 L)中放入少量的只吸附氧气的吸附剂,保持真空。打开旋塞C,放置片刻,容器内的总压强变为0.6×105 Pa,这时气体中氮气和氧气的分子数之比最接近的数值是(吸附剂的体积可忽略不计)(    )

A.8∶1

B.10∶1

C.12∶1

D.14∶1

题型:选择题

阅读理解。

     The other day, my friend Jane was invited to a 40th birthday party. The time printed on the invitation was

7:30 pm. Jane went off with her husband, expecting a merry evening of wine, food, and song.

     By 9:45, everybody was having great fun, but no food had appeared. Jane and David were restless. Other

guests began whispering that they, too, were starving. But no one wanted to leave, just in case some food was

about to appear. By 11:00, there was still no food, and everyone was completely off their heads. Jane and

David left hungry and angry.

     Their experience suggests that the words on the printed invitations need to be made clearer. Everyone reads

and understands the invitations differently. Most of us would agree that 6:30-8:30 pm means drinks only, go

out to dinner afterwards; 8:00 pm or 8:30 pm means possible dinner, but 9:30 pm and any time thereafter means no food, eat beforehand, roll up late.

     But this is not always the case. If asked to a students' party at 6:30 pm, it is unaccepted for guests to appear on time. Being the first to arrive-looking eager-is social death. When my mother is asked to a party at 6:30, she

likes to be there, if not on time, then no later than seven. My age group (late thirties) falls somewhere between

the two, but because we still think we're young, we're probably closer to student-time than grown-up time.

     The accepted custom at present is confusing, sometimes annoying, and it often means you may go home

hungry, but it does lend every party that precious element of surprise.

1. The underlined words "off their heads" probably mean ______.

A. tired

B. crazy

C. happy

D. encouraging

2. Jane and David's story is used to show that ______.

A. party invitations can be confusing

B. party-goers usually get hungry at parties

C. people should ask for food at parties

D. birthday parties for middle-aged people are dull

3. For some young people, arriving on time for a students' party will probably be considered ______.

A. very difficult

B. particularly thoughtful

C. friendly and polite

D. socially unacceptable

4. What is the general idea of the text?

A. It's safe to arrive late just when food is served.

B. It's wise to eat something before going to a party.

C. It's important to follow social rules of party-going.

D. There's no need to read invitations carefully.

题型:选择题

有关良性肿瘤的特点中,下列错误的是()。

A.细胞分化程度高

B.多呈膨胀性生长

C.不会威胁生命

D.有包膜或与周围有明显界限

E.少数可以恶变

题型:选择题

目前,最理想的控制中枢性尿崩症的药物是

A.去氨加压素(弥凝)

B.加压素

C.垂体后叶素

D.氢氯噻嗪

E.卡马西平

题型:选择题

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