Science and technology (S&T) capabilities are fundamental for social and economic progress in developing countries; for example, in the health (19) ______ , scientific research led to the development and introduction of oral rehydration therapy, which became the cornerstone of international (20) ______ to control diarrheal diseases. Research also established that two cents worth of vitamin A given to children every six months could (21) ______ child mortality in many countries by over one-third. In agriculture, rice-wheat rotation techniques have significantly enhanced food production in South Asia. In Central America, scientifically based natural resource management has been essential in developing the tourist (22) ______ , a major source of foreign currency. International programs based on S&T are critical components of U.S. foreign policy, and particularly foreign assistance activities. Foreign assistance, probably more than any other international endeavor, (23) ______ opportunities for representatives of the U.S. government and its partners to join with political and economic leaders, intellectuals, and activists of dozens of countries in continuing, constructive dialogues and in concrete projects designed to enhance the quality of life of hundreds of millions of people. S&T are often the keystones for (24) ______ projects. The shared political and economic dividends from these activities can be enormous. 19. A. sector B. area C. region D. item 20. A. nations B. sessions C. owners D. efforts 21. A. mention B. reduce C. survey D. conflict 22. A. career B. branch C. industry D. agriculture 23. A. surround B. provides C. combines D. impresses 24. A. friendly B. beautiful C. delicate D. successful giải thích nữa nha mọi người ơi.