第10题: [单项选择]When did NASA start working on a successor to the shuttle A. One year before the Columbia disaster. B. One year after the Columbia disaster. C. Immediately after the Columbia disaster. D. Years before the Columbia disaster. 参考答案:D 答案解析:原文第一段实际上已经提到,在调查哥伦比亚号失事原因之前,NASA就已着手开展 工作了,倒数第三段第一句提到研制工作很多年前就开始了,故答案为D。