题目

存在于RNA中而不存在于DNA，存在于叶绿体而不存在于线粒体，存在于动物细胞质而不存在于植物细胞质中的糖类物质分别是（）      A．核糖、葡萄糖、糖原    B．  脱氧核糖、核糖、纤维素      C．核糖、脱氧核糖、麦芽糖    D． 脱氧核糖、葡萄糖、淀粉 答案：A 阅读填空 Joe was born in 1931．As a boy, he had a dream of becoming a doctor．But in 1948, when he was 17, he had to work to help support his family．He served in the army for over ten years．Then he worked in his hometown for 20 years．But he still kept his dream of going back to school．In 1979, at the age of 48, he finished his high school and became a college student．In 1986, he completed his work on his master’s degree．Today at 56, Joe is studying for his doctor’s degree．His dream is coming true．