1 . 语法填空

The Sahara Desert is the world’s     1     (large) hot desert, located in North Africa.     2     (it) area is about 3.5 million square miles. This     3     (make) it almost as large     4     the United States of America.

The Sahara Desert is famous for many large sand dunes (沙丘), some of     5     can reach more than 600 feet high.

The Sahara Desert has been largely dry and with little plant life more than 5，000 years. Before this time, it was far wetter. This allowed more plants     6     (live) across the desert. There is evidence that many types of river animals have lived in the Sahara Desert. These have been found     7     (main) in southeast Algeria.

The climate of the Sahara Desert has changed over several thousands of years. The area is smaller than it was during the last ice age. It was the end of the last ice age that brought a high level of rainfall to the Sahara. This was between 8000     8     6000 BC. Since this time, the northern part of the Sahara has dried out. Though the southern Sahara still receives rain during rainy season, it is still     9     (little) than before.

Modern times have seen a few     10     (development) for the Sahara. One of these is that mines have been built to get the most from the natural resources (资源) within the area.

2 . 阅读下面短文，在空白处填入适当的单词或括号内单词的正确形式。

The 500-meter Aperture Spherical Radio Telescope（FAST）, also known as China's Tianyan or "Sky Eye", has     1    （official）opened to global scientists since April, 2021.

As we know, radio telescopes    2    （design）to "listen" or "receive" signals emitted from the universe. With specialized antennas（天线）and radio receivers, these telescopes can detect radio waves from stars, galaxies and black holes. The data collected in turn help scientists    3    （good）explore the universe. It will also be used occasionally to search for alien life.

The giant radio telescope will also help find more pulsars（脉冲星）, which send out steady signals and waves in a regular rhythm. Scientists use pulsars    4    （study）the extreme states of matter, measure cosmic（宇宙的）distances and track time in an ultra-precise（超精密）way. So far, it    5    （discover）more than 240 pulsars.

    6    （locate）in southwest China' s Guizhou Province,    7    largest single-dish radio telescope of the world was completed in 2016. It was put to use    8    January 11, 2020. FAST is now the only "Sky Eye"    9    humans can use to observe cosmic waves. It has immense potential to detect fast radio bursts and gravitational waves,     10    （provide）data support for research into the physical process of the Big Bang, according to experts at the NAO.

3 . 阅读下面材料，在空白处填入1个合适的单词或括号内单词的正确形式。

Each year, some 50 to 100 million animals are used in scientific research around the world. Animal testing allows researchers to develop new medicine and     1    (treat), advancing the field of medicine and improving the health of society. For example, many drugs used to treat or prevent cancer, HIV, etc., have resulted from tests     2    (do) on animals.

Animal testing also makes     3     possible for scientists and researchers to test the safety of medicine. Drugs may pose significant risks to humans, so testing them on animals first     4     (give) researchers a chance to determine their safety before human trials are performed.

However, a significant number of animals     5    （harm) or die as a result of experiments and testing each day. Those who oppose animal testing say such experiments are     6     (stress) and sometimes painful for animals. Opponents also argue that animals are quite different from humans,     7     (make) the results of animal testing unreliable. Thousands of activists worldwide are campaigning for raising awareness and demanding an end     8     animal testing.

Animal testing has taught human beings a great deal and saved a large number of     9     (life). It needs to be continued, even if that means animals sometimes suffer. However, new measures should be taken to reduce the number of animals used in experiments and improve the way in     10     scientific research is conducted.

4 . Tu Youyou encouraged scientists to ________ (far) explore the treasure house of traditional Chinese medicine and raise it to a higher level.(所给词的适当形式填空)