Cloning has two major uses. First, gardeners use it to produce large     1     (quantity) of plants for sale. Second, it is valuable for research on new plant species and for medical research on animals. Cloning plants is fairly straightforward, while cloning animals is much     2     (complicated) and difficult. Over the years, many scientists failed in their attempts to clone animals, but their determination and     3     (patient) paid off in 1996 with a breakthrough-the cloning of Dolly the sheep.

Tu Youyou was awarded the Nobel Prize in 2015 for her research,     1     led to the discovery of artemisinin. Artemisinin has saved a large number of lives since it was discovered. After     2     (graduate) from university, Tu Youyou worked at the China Academy of Traditional Chinese Medicine. In 1967, Tu Youyou     3     (choose) as a researcher of a team of scientists with     4     purpose of discovering a new treatment for malaria.

For the past few years, Wuzhen has hosted the World Internet Conference,     1    makes life in this town much more convenient than it used to be. Residents here can surf online as    2    (easy) as in large modern cities. Plus, they can download movies and music at high speeds. The Internet has even changed Wuzhen’s transport! Both residents and    3    (tourist) can use the public bike system. Bikes can be rented by    4    (use) online apps — no need for paperwork or cash payment.

Natural cloning has taken place for generations. A sheep called Dolly was the first mammal to be cloned     1     (successful). Since Dolly, more than 20 mammal species     2     (clone) including camels and goats. In 2018, China announced that two monkeys had been cloned. In     3     (compare) with other species, scientists have had to work hard to break the technical barrier to get primates (灵长类动物) with edited genes. Scientists say that major breakthrough offers the potential     4     (create) monkeys with identical genes to give more accurate research results.

A hybrid is a cross between two or more varieties of a species which usually attains a higher yield than conventional crops. However,     1    it was possible to develop a hybrid of self-pollinating plants such as rice was a matter of great debate. The common assumption then     2     (be) that it could not be done. Through intense effort, Yuan overcame enormous technical difficulties to develop the first hybrid rice     3    could be used for farming in 1974.

The gesture for “OK” has different meanings in different cultures. In Japan, someone who witnesses another person     1     (employ) the gesture might think it means money. In France, a person encountering an identical gesture may interpret it     2     meaning zero. However, you should avoid making this gesture in Brazil and Germany, as it is considered     3     (polite).