未育妇女人流后应采取的有效避孕措施包括（）A.宫内绝育器 B.男_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题单项选择题

未育妇女人流后应采取的有效避孕措施包括（）

A.宫内绝育器

B.男用避孕套

C.杜绝性生活

D.女性绝育术

答案

参考答案：B

选择题

根据遗传学原理，能迅速获得纯合新品种的育种方法是[ ]

A．单倍体育种

B．多倍体育种

C．杂交育种

D．诱变育种

填空题

An Event of Imagination

The year is 2094. It has been announced that a comet is heading towards the Earth. Most of it will miss our planet, but two pieces will probably hit the southern half of the Earth.
On 17 July, a piece about/for four kilometers wide enters the Earth’s atmosphere with a massive explosion.
About half of the piece is destroyed, but the remaining part hits the South Atlantic at 200 times the speed of sound. The sea boils and a huge hole is made in the seabed. Huge waves are created and spread outwards from the hole. The wall of water, a kilometer high, rushes towards southern Africa at 800 kilometers an hour. Cities on the African coast are totally destroyed and millions of people are drowned.
Before the waves reach South America, the second piece of the comet lands in Argentina.
Earthquakes and volcanoes are set off in the Andes Mountains. The shock waves move north into California and all around the Pacific Ocean. The cities of Los Angeles, San Francisco and Tokyo are completely destroyed by earthquakes. Millions of people in the southern half of the earth are already dead, but the north won’t escape for long. Because of the explosions, the sun is hidden by clouds of dust, and temperature around the world falls to almost zero. Crops are ruined. The sun won’t be seen again for many years. Wars break out as countries fight for food. A year later, no more than 10 million remain alive.
Could it really happen In fact, it has already happened more than once in the history of the Earth. The dinosaurs (恐龙) were on the Earth for over 160 million years. Then 65 million years ago they suddenly disappeared. Many scientists believe that the Earth was hit by a piece of object in space. The dinosaurs couldn’t live through the cold climate that followed and they died out. Will we meet the same end

Reasons	Results
One piece hits the South Atlantic at 200 times faster than the speed of sound.	The sea (46) and a huge hole is made in the seabed. A tsunami(海啸) hits southern Africa, (47) cities on the African coast, and (48) millions of people.




A (49) (50) happens when the four-kilo- meter-wide piece of comet enters the Earth’s (51)	The sun is (52) . by clouds of dust and the temperature falls to almost zero, (53) crops. Wars break out for food and only 10 million people remain. The human beings are (54) the danger of (55) out.