下列成语运用正确的是( )
A:船舱鼓鼓的,又像一个忍俊不禁的笑容,就要绽开似的。
B:不少人对工作很负责人,拈轻怕重,把重担留给自己,让别人挑轻的。
C:他以医疗为职业,对技术精益求精。
D:对同志对人民不是满腔热忱,而是冷冷清清,漠不关心,麻木不仁。
1956年中共八大后的十年,社会主义建设发生严重失误,国民经济严重倒退,并未取得建设成就。( )
图是人体内的细胞在分裂过程中每条染色体的DNA含量变化曲线.下列有关叙述中正确的是( )
Gypsies
According to the linguistic and genetic researches, ancestors of the Gypsies left the land of India in the amount that did not go beyond 1,000 people. Today there are about 10 million Gypsies in the world. Some scientists believe that Gypsies were Egyptians.
Sumerians
Sumerians must be the mysterious people in the ancient world. We know nothing about their origin and nothing about the origin of their language. The Sumerians were rather advanced—they became the first in the Near East to use a wheel, to create an irrigation system and their unique writing. And besides, they were impressively good at maths and astronomy.
Maya
Some scientists believe that they are connected to legendary atlantes (男像柱), others suppose their ancestors were Egyptians. It's thought that the Maya created an efficient agricultural system and had deep astronomy knowledge. Their calendar was used by other people of Central America. Maya applied the hieroglyphic writing (象形文字) system. Now it seems that the Maya came from nowhere and disappeared nowhere.
如图为甲乙两质点做直线运动的x﹣t图象,由图象可知( )