【单选题】The technicians are working hard to _______ the design of the new car to make it more competitive in the overseas market.
【单选题】The technicians are quite confident of their success, because the results of the first experiments are very _____.
【单选题】The technicians are working hard to __ the design of the new car to make it more competitive in the overseas market.
【简答题】在原子序数为 1~20 号的元素中,用适当的化学符号填写下列空白(稀有气体除外).半径最小的元素是______;半径最大的元素是______;氧化性最强的单质是______;还原性最强的单质是______;最高价氧化物对应水化物中碱性最强的化合物是______;最高价氧化物对应水化物中酸性最强的化合物是______;最高价氧化物对应水化物中呈两性的化合物是______;最稳定的气态氢化物是____...
【单选题】下列物质的用途与性质对应关系错误的是( )
C.
铁粉可做食品保鲜剂——铁粉可以和空气中的氧气和水反应
【判断题】按GB7588—2003《电梯制造与安装安全规范》规定,曳引钢丝绳的安全系数是指125%额定载荷的轿厢停靠在最低层站时,一根钢丝绳的最小破断负荷(N)与这根钢丝绳所受的最大力(N)之间的比值。
【单选题】听力原文:(A) The technicians are testing their telescopes. (B) The scientists are working in the laboratory. (C) The physicians are performing an operation. (D) The soldiers are cleaning their uniforms.