用括号内所给动词的适当形式填空，必要时可加助动词或情态动词。

     Katrina is twelve years old. In the past(在过去)，she hardly ever   1   (do) any exercise. She didn’t like    2    (drink) water, too. So she looked very     3    (healthy). She didn’t feel like doing anything. On weekends and during vacations, she always watched TV at home. Also, she was very quiet in class. She never put up her hand to answer the teacher’s questions.

     A few weeks ago, Katrina told her parents she often wanted    4    (sleep)in class. She wanted to listen carefully in class, but she couldn’t. Her parents were very worried about her. At last, they decided   5   (take) her to see a doctor. The doctor told Katrina that she should    6   (exercise) more.

     Now Katrina exercises three times a week. She often walks or joins in other activities. And she is good at    7   (swim). How happy she is! Tomorrow is Saturday, she    8   (plan)to go bike riding with her friends Tina and Tara. Now she does well in her school work and has more friends.

甾体化合物结构特点是

A．有一个环戊烷并多氢菲的结构
B．有一个环戊烷并多氢菲的结构，分别为A、B、C、D环
C．有一个环戊烷并多氢菲的结构，分别为A、B、C、D环，A/B环和C/D环稠合处各有一个甲基
D．有一个环戊烷并多氢菲的结构，分别为A、B、C、D环，A/B环和C/D环稠合处各有一个甲基，在D环的17位常有一个碳链
E．有一个环戊烷并多氢菲的结构，分别为A、B、C、D环，A/B环和C/D环稠合处各有一个甲基，在D环的17位常有一个碳链或一个含氧基团