IgG指数_________提示中枢神经系统内的IgG合成并提示可能为_________。
参考答案：>O.7；多发性硬化
奥运会从第几届开始设游泳比赛？
- Sam, I called you yesterday evening, but no one answered.
- Oh, sorry. I _______ a shower at that time. [ ]
A. took
B. am taking
C. take
D. was taking
