不定项选择
石英岩由石英砂岩和硅质岩变质而成,矿物成分以石英为主,其次为云母、磁铁矿和角闪石。
单项选择题 最适宜的锻炼频度是每周进行( )次 A. 1-2 B. 2-3 C. 3-4 D. 4-5
多项选择题 2、大学安全与保护,需要()
单项选择题 The Hawaiian Islands, which are situated in the Pacific, became __________ state of the United States in 1959.A.the fifthB.the fifteenthC.the fiftiethD.the fourth