题干
When first __________ to the market, the computer software was not a success due to its complexity in operation.
A：introducing
B：being introduced
C：introduced
D：to be introduced
答案(点此获取答案解析）
C
中，
分别是其左右焦点，若
，则该椭圆离心率的取值范围是
中的氯离子浓度与50 mL 1 mol·L-1的AlCl3溶液中氯离子浓度相等的是