下列发生了细胞分化且能体现体细胞全能性的生物学过程是( )。
A.玉米种子萌发长成新植株
B.小鼠骨髓造血干细胞形成各种血细胞
C.小麦花粉经离体培养发育成单倍体植株
D.胡萝卜根韧皮部细胞经组织培养发育成新植株
请仔细观察下面这幅漫画,自拟题目,写一篇不少于800字的议论文。
注意:不要套作,不得抄袭,不写错别字,卷面整洁。
X、Y、Z、W四种短周期元素,有关数据如下表:下列叙述正确的是( )
元素代号 | X | Y | Z | W |
原子半径/pm | 66 | 70 | 143 | 160 |
主要化合价 | -2 | +5、+3、-3 | +3 | +2 |
A.W和Y形成的化合物为共价化合物
B.Y的最高价氧化物对应的水化物为强酸
C.Y的简单气态氢化物的沸点高于X的简单气态氢化物
D.工业上经常采用电解Z的氯化物溶液制备Z单质
Let’s focus on what you bring to society ______ on how much money you earn.
A. rather than B. more than C. other than D. less than
读某地质剖面图(③为石灰岩),读图完成28题。
28图中 岩石按照形成的顺序,由老到新的排列最可能的是
A.①②③④⑤ B.③⑤①②④
C. ③①②④⑤ D.⑤①②③④
西方社会在发展过程中形成了平等、法制的社会观念,而古老的中国则衍生出对权力的膜拜和鲜明的等级尊卑秩序。造成这种差别的主要原因是
A.生活方式上动与静的差别 B.经营方式上开放与封闭的差别
C.经济形态上商品经济与农耕经济的差别D.文化观念上个人主义与集体主义的差别
新航路开辟后西欧商业领域出现了一次重大变革。这场变革的具体表现有
①以西欧为中心的世界贸易开始形成 ②股份公司、证券交易所纷纷出现
③欧洲商路中心转移到了大西洋沿岸 ④大量金银流入,造成了物价上涨
A.①②③④ B.①②③ C.②③④ D.①②④
下图是我国某地城乡居民年人均收入表,图中的城乡差距最小年的出现是因为
A. 社会主义市场经济体制目标的建立 B. 实行从沿海到内地的开放格局的确立
C. 农村改革已全面展开,城市改革刚刚起步
D. 对国有企业进行改革,建立现代企业制度
如图所示,在坐标系的第一象限内存在磁感应强度的大小为B、方向垂直纸面向外的矩形有界匀强磁场,在第三象限存在与y轴正向成30°角的匀强电场.现有一质量为m、电荷量为+q的粒子由静止从电场的P点经电场加速后从O点进入磁场.不计粒子的重力.
(1)在UPO较小时,粒子从磁场下边界射出,求此时粒子在磁场中运动的时间t;
(2)增大UPO,粒子将从磁场右边界射出,求PO间的电势差UPO的范围.
(3)继续增大UPO,粒子将从磁场上边界射出,求磁场上边界有粒子射出的区域的长度.
设为正整数,集合
.对于集合
中的任意元素
和
.
记.
(1)当时,若
,
,求
和
的值;
(2)当时,设
是
的子集,且满足:对于
中的任意元素
,当
相同时,
是奇数;当
不同时,
是偶数.求集合
中元素个数的最大值;
(3)给定不小于2的,设
是
的子集,且满足:对于
中的任意两个不同的元素
,
.写出一个集合
,使其元素个数最多,并说明理由.
利用Cu和浓硫酸制备SO2的反应涉及的装置,下列说法正确的是
A.用装置①制备SO2 B.用装置②检验和收集SO2
C.用装置③稀释反应后溶液 D.用装置④测定反应后溶液中c(H+)
Chinese New Year is approaching and preparations are underway around the world. Here are some Chinatowns for those outside of China wishing to mark the day.
London
Although it may not be as large or as long-built as others, having only become a center for the Chinese community during the 1950s, London’s Chinatown is a perfectly formed little firework that knows how to
see in the year with a bang. Decorated with red lanterns (灯笼), previous years have seen shows with acrobatics (杂技), martial arts (武术), dance and opera nearby.
San Francisco
San Francisco’s Chinatown is perhaps the most famous in the United States. The city was the main entry-point for Chinese who had crossed the Pacific to the USA during the early 19th century. Between the Grant Avenue and the Stockton Street, this historic area is a local treasure, attracting more visitors per year than the Golden Gate Bridge.
Bangkok
With an about 100-year-old history, the Thai capital’s Chinatown contains complex streets offering all kinds of tasty treats, clothes, toys and antiques. Sunday market days are such a good time to get the full atmosphere of the neighborhood. The area is also known for its gold dealers, whose shops line the road.
Mauritius
Found in Port Louis, this Mauritian Chinatown shows the island nation’s rich multicultural diversity. Established in the early years of the 20th century by settlers from China, its tiny shops and restaurants serve locals and visitors. During the Chinese Spring Festival, the most exciting sight is the Dragon Dances on Rue Royale when Chinese musicians and dancers perform the traditional Lion dances through the streets.
21. According to the text, which of the following has the longest history?
A. London’s Chinatown. | B. Bangkok’s Chinatown. |
C. Mauritius’s Chinatown. | D. San Francisco’s Chinatown. |
22. What’s special about Bangkok’s Chinatown?
A. It is crowded with Chinese restaurants. |
B. It was the major entrance for the Chinese. |
C. It is well-known for its gold business. |
D. It is where you can enjoy fireworks. |
23. If you want to enjoy the Dragon Dances, you can go to ______.
A. Rue Royale in Port Louis, Mauritius. |
B. the Sunday market in Bangkok. |
C. the Grant Avenue in San Francisco. D. the Chinese community in London. |