A．useful　　　　　　　　　 B．useless

　　C．harmful D．powerful

　　解析：选A　推理判断题。画线句表明，虽然沙尘暴能移动沙丘并毁坏农作物，但它不是毫无益处的。注意"a sandstorm is not without benefit"表示"不无裨益"，是双重否定表示肯定意义。故选A。

　　3．According to the writer, a sandstorm ________.

　　A．is the result of human activities

　　B．can be prevented

　　C．can't completely disappear on the earth

　　D．can't be forecast

　　解析：选C　推理判断题。根据最后一段可知，作者认为沙尘暴是一种自然现象，不能完全被控制，也就不会完全消失，并且它也不是人为的后果。故选C。

　　B

　　In Kenya, blind students and those with poor eyesight were still using Braille (布拉耶盲文) books for their studies until recently. Their books used the Braille system of raised dots to represent words and numbers. Those with limited or no eyesight can "read" by touching those markings. But Kenyan schools for the blind are now beginning to use technology that provides material in an audible (听得见的) form.

　　Seventeen­year­old Lucas Mwanzia is visually impaired (受损的). For the past two years, he has been attending computer classes at the Thika School for the Blind. He said, "The technology has opened doors that once were closed. Braille books are costly and you have to spend a lot of money buying one. With computers, the books are available at little or no cost. So we can download the books to read and when we finish reading we just need to close the program." Zachary Muasya was born blind. He is now one of the school's teachers. He has been teaching the students how to use the technology for about two years now. "The assistive technology equips the learners with many skills that really make them independent in life. They can read books, magazines and newspapers by themselves."

The school started using assistive technology six years ago. It enables blind and visually­impaired students to get information from computers and iPads. The assistive technology costs ＄1,000 to set up. But a non­governmental organization called InAble has provided it for the schools at no cost. Four out of Kenya's 11 schools for the blind are using the technology. InAble says it will provide the financing for the remaining schools to join the effort. Peter Okeyo, the program manager at InAble, says blind students using the technology may still have difficulty when they move to higher education. Students who have