在计算机中，8位无符号二进制整数可表示的十进制数最大的是（）。
A.128
B.255
C.127
D.256
参考答案：B
用动词的正确时态填空。
1. He____ (study) at this school ten years ago.
2. They ____ (watch) TV at home since 8:00.
3. It's 9:00 now. All the students ____ (have) an English class in the classroom.
4. — ____ you ____ (see) any movie recently?
—Yes, I ____ (see) Harry PotterⅢ yesterday.
5. Our English teacher ____ (teach) English at this school for about 20 years.
6. Mary's father likes ____ (climb) mountains, so climbing mountains is his hobby.
7. As drivers, they must ____ (obey) traffic rules.
8. She ____ (scream) when she saw a long snake.
9. We didn't go home until we finished ____ (clean) the classroom.
10. Do you know how ____ (make) a vegetable salad?
下列哪一个药物在钠石灰中最不稳定:
nglish teacher ____ (teach) English at this school for about 20 years.