阅读下列短文，从每小题所给的A、B、C、D四个选项中选出最佳选项。
Look at the girl. Her name is Lucy. And this lovely girl is her twin sister Lily.1parents are both （两者都）teachers. They work hard.
Lucy and Lily2at No.4 Middle School. They go to school3Monday to Friday. They have no classes on Saturdays and Sundays. They have breakfast at 6:30. They go to school at 7:00. Classes
4at eight. They have four5in the morning and three in the afternoon. They have6at 12: 15. At 3:50,they have sports.
Lucy and Lily study Chinese, math, English, geography, physics, history and other lessons. Lucy's favorite7is music,8it's relaxing. Lily likes science best. She thinks it's difficult 9interesting.
Their parents like reading. They often read books at home. Their parents are strict(严厉地)with them, but sometimes they are very kind and friendly to their children. Lucy and Lily love their10 very much.
的定义域为实数集，
（e为自然对数的底），则必有（ ）