根据句意和首字母提示填空，完成下列句子。
1. His bike is broken, he has to walk to school i_______ of riding.
2. Little Tom is t_______ of speaking aloud, he's shy.
3. When we heard the bad news, we couldn't help s_______ laughing.
4. A spider is a kind of i_______.
5. He became very i_______ in music at the age of five.
6. Annie used to be quiet, but now she's very o_______.
7. I didn't go to bed u_______ nine yesterday evening.
8. Lucy used to have short hair, but now her hair is l_______ than before.
9. Sorry, I can't join you. I h_______ to study for a test.
10. She is u_______ to the life here.
11. Don't w_______ about things so much. Take it easy.
12. It seemed that she has c_______ a lot. She's more outgoing.
13. He's f_______ to us. We're very thankful.
14. Don't you r_______ me, I'm John, your old classmate.
15. The teacher looks so s_______. What happened?
16. He still argues, t_______ he knows he's wrong.
17. They can't a_______ to buy a new TV set.
=15V，Ub=-9V，Rc=3kΩ，Rb=20kΩ，β=40，当输入电压U1=5V时，要使晶体管饱和导通，Rx值不得大于（）kΩ。（设
=0.7V，集电极和发射极之间的饱和电压
）
