DL451—1991《循环式远动规约》要求远动通道的传输误码率一般不大于（）。
A.10-5
B.10-4
C.10-3
D.10-2
参考答案：A
已知a+b=1，ab=-3，求（a-b）2的值．
根据汉语或句意，写出句中所缺的单词。
1. Jack has many _______(爱好). One of them is growing flowers.
2 . We should not eat too many sweets. It is bad for our _______ .
3. My parents are going to Guilin on _______. （假日）
4 I know there are eleven p_______ in a football team.
5. We have music lessons on _______ ( the third day in a week) .
