单选题 Drug development is complicated, time-consuming, and costly. Thousands of chemical ______ must be tested to find one that can achieve a desirable result.

单选题 The UN is a(n) ______ that has done a lot in providing humanitarian assistance to affected regions in Africa.

单选题 The International Monetary Fund (国际货币基金组织) said this week that global growth would slow this year as levels of ______ rise.

单选题 Many older workers, generally those over 40, say they will need to work longer because of the ______.

单选题 If a vaccine is identified, production should be "globally distributed" to guard against "vaccine ______," she said.

单选题 The study claims that up to 60 million people in Africa will be pushed into extreme poverty—that erases all the progress made in ______ in the past three years.

单选题 A(n) ______ is someone who creates ideas and plans, especially those carried out by a business or government.

单选题 ______ is the degree to which total income is distributed unevenly throughout a population.

单选题 The statement said that ______ is essential to deal with the health and economic impact of the COVID-19 virus.