下列实验操作正确的是()

题型:选择题

问题:

下列实验操作正确的是( )

考点:测容器—量筒称量器—天平加热器皿—酒精灯常见仪器和装置的用途
题型:选择题

质量为M的木块静止在光滑的水平面上,质量为m的子弹以水平速度v0在下面两种情况下击中木块,并最终留在木块内.第一次木块被事先固定住,子弹在木块中钻入深度为s1,经历时间为t1;第二次木块不固定,子弹在木块中钻入深度为s2,经历时间为t2.两次击中木块过程中,子弹受的平均阻力相同.比较s1和s2,t1和t2,有(  )

A.s1=s2

B.s1<s2

C.t1<t2

D.t1>t2

题型:选择题

George Dawson wrote a book called Life Is So Good. The book is filled with stories from George's life.小题1:    It is surprising that George learned to read just two years before he wrote the book. When George was 8, his dad sent him to work.   小题2:   George did many jobs. All the time, he took care to keep it a secret that he couldn't read signs.   小题3:  

George helped his children with their homework when they were at school. They read their homework to him. He said this would help them learn better. 小题4:   He told them his secret when they started high school. Then they helped keep the secret. When George was 98, he heard about the evening classes near his home. He still had a dream that he would learn to read.    小题5:  He said, “A wise man can change, but a fool stays the same.” With the teacher's help, he wrote his book Life Is So Good two years later.

A.Because food became more important than school at that time.

B.George wrote it in 1998 when he was 100 years old.

C.He went to class and learned the alphabet(字母) in less than two days.

D.He had to ask people things and tried to remember them.E. The book is so meaningful to both the writers and the readers

F. They didn't know their dad couldn't read.

题型:选择题

Questions from 36 to 40 are based on the following passage:China’s entrance into the World Trade Organization(WTO) will benefit not only itself but the whole world, said an article in People’s Daily.For the last nine years negotiations have gone on concerning restoring China’s status in the General Agreement on Tariffs and Trade (GATT),which is replaced by WTO. The negotiation have drawn attention from all over the world.Only when consensus is reached on key issues, can the final decision, involving more than 100 member states , be made.It is expected that China’s bid will eventually pass, though final details and a timetable have not been decided yet, said the People’s Daily.Over the past years, China has taken important steps to conform with international trade regulations based on the Uruguay-round talks. It is clear that China has made its markets more open, both in commercial and tertiary industries. Since 1992, a series of measures has been taken in lowering tariff rates and reducing non-tariff barriers.These reforms demonstrate China’s readiness to join the WTO. Serious disputes, however,still remain between China and some key member states over the obligations China should undertake.China should be responsible for reform compatible with its current development level, the article stressed. In future negotiations, we should insist on this point and give the member states a clearer understanding of the practical situation in China.China has a population of 1.2 billion, which increases by 10 million each year. The government must be very cautious in reforms to prevent dramatic economic downfalls, which may have disastrous results not only in China but around the world.China’s per capita income remains less than $500, there are still 70 million people who do not have enough for basic food and clothing. The negotiators should bear in mind the country’s development level when they decide the obligations China should assume.Otherwise, negotiation results will be meaningless, or worse; they could stifle the Chinese market. It is like the old Chinese saying: “Killing the hen to get the eggs.”China is in transition from a planned economy to a market one. With such a big population and large economic development scale, a transitional period is necessary for any new reform measure. This is also the case when adopting some international practice.

39.According to the passage, what kind of measures has been taken in China since 1992 ( )

A.lowering tariff rates

B.reducing non-tariff barriers

C.opening all markets

D.Both A and B

题型:选择题

下面对串级调节系统中副回路描述正确的是()

A.副回路的存在使调节系统的工作频率有了较大的提高

B.副回路是一个快速随动系统,使串级调节系统具有一定的适应能力

C.副回路的存在提高了调节系统的抗干扰能力

D.副回路的作用不大

题型:选择题


某大型输水工程在嘉陵江上中游建设,工程主要由水利枢纽、库区、输水干渠和灌区组成。现知:该段河流有白鲟、胭脂鱼等珍稀水生生物和多处鱼类产卵场、越冬场;坝址下游有农田和县城;干渠穿过一片候鸟栖息的湿地保护区;灌区200万亩将在灌草地上建设。

该工程应进行几个时段的生态评价

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