______ I failed in English a third time, I had no doubt about my gift for foreign languages. A. By the time B. Until C. After D. Unless 答案:B 考查连词。Until表示直到的含义。 下列物质与其用途完全符合的有( )条 ①CaCO3—制玻璃; ② SiO2—制光导纤维; ③AgBr—照相底片感光剂; ④NaCl—制纯碱; ⑤ Al2O3—焊接钢轨; ⑥NaClO—消毒剂; ⑦Fe2O3—红色油漆; ⑧MgO—耐火材料 A.5 B.6 C.7 D.8