9.________ that new homes cost more than older homes, but that is not true across the country anymore.

A. It used to be
B. It is used to be
C. It used to being
D. It is used to being

2.Exercise should include nonstop activity performed for 30 or more minutes in order to keep the heart rate up. In other words, it should be done in a(n) ________ way.

A. immense
B. irregular
C. continuous
D. routine

6.It is not that colorful sunshine, loud music and exciting games could attract hundreds of visitors to charity fun fairs, but _______ warm-hearted people were willing to help the victims in poverty-stricken areas.

A. because
B. as
C. since
D. that

1.Jane wanted to break up with her boyfriend, but she ________ herself at the last minute and decided to give it another try.

A. regretted
B. overwhelmed
C. strained
D. reversed

11.The woman who died in a car crash last Saturday in the suburbs has been ________ as Kate Johnson, a 25-year-old office clerk.

A. justified
B. identified
C. notified
D. classified

Poor Laura! I feel so sorry for her. When she fell, she hurt her arm and, ________, broke her glasses.

A. in advance
B. in addition
C. over time
D. on the other hand

Don't worry too much, Jane. Your son ________ home already. Let's go back and check it out.

A. returned
B. will return
C. has returned
D. may have returned

Directions:For each of the following sentences there are four choices marked A, B, C and D. Choose the best one to complete each sentence.1.If you don't ________ cooking today, we can go out to eat at the new restaurant.

A. would like
B. go on with
C. feel like
D. figure out

如果采用的晶振的频率为12MHz，定时器/计数器工作在方式0、1、2下，其最大定时时间各为多少？

程序设计题：利用定时器T1的中断来使P1.0控制蜂鸣器发出2kHz的音频信号，假设系统时钟频率为12MHz。请利用Proteus虚拟仿真编程仿真，线上提交C51程序及Proteus仿真结果（仿真输出波形用示波器显示），并提交纸质档C51程序及仿真结果。文档要求：1、文档条理清楚；2、每行程序有中文注释；