Jack is a schoolboy. He小题1: c______ from England. This year, he is thirteen years old. He 小题2:l_______ in a small town near London(伦敦). He lives with his grandmother. His parents 小题3:w________ in London. They come back home to visit Jack at 小题4:w_______. Jack小题5:g______to school by bike every day. At school, he likes studying all the 小题6:l_______. He is good 小题7:a_____ English. He listens to the teachers carefully(认真) in class. He works very hard at his lessons. After school, he does his小题8:h ______. He 小题9:w________ TV only on Sunday evening. Jack is a good boy and his parents 小题10:l_____him.

0.01mol／L碘标准溶液的（）容易发生变化，应在使用时配制。

A.浓度；

B.颜色；

C.反应速度