下列叙述中与小肠的消化作用无关的是()
A.小肠内表面有许多环形皱襞、小肠绒毛
B.小肠绒毛内有大量的毛细血管和毛细淋巴管
C.小肠内有胆汁
D.小肠内有肠液和胰液
参考答案:A
补全对话。(填入适当的单词)
A: 1. _____ do you get to school?
B: I 2. _____ the bus.
A: How 3. _____ is it 4. _____ your home 5. _____ school?
B: It's 2.5 kilometers.
A: How 6. _____ does it 7. _____ you to get to school?
B: 8. _____ takes twenty minutes. What about you?
A: I often 9. _____ to school because my home is only fifteen meters 10. _____
school.
下面一段叙述中,有Ⅰ~Ⅳ共4个空缺: 8237接收到通道请求(Ⅰ)信号后,向CPU发出DMA请求信号(Ⅱ),CPU接收到该信号后,在当前总线周期结束之后让出总线,并使总线允许信号(Ⅲ)有效:当 8237获得CPU送来的该信号后,便产生(Ⅳ)信号送到相应的外设喘口,表示DMA控制器响应外设的DMA请求,从而进入DMA服务过程。关于填写Ⅰ~Ⅳ的选项中,正确的是( )。
A.Ⅰ~Ⅳ分别为DREQ、DACK、HRQ、HLDA
B.Ⅰ~Ⅳ分别为DREQ、HLDA、DACK、HRQ
C.Ⅰ~Ⅳ分别为HRQ、DREQ、DACK、HLDA
D.Ⅰ~Ⅳ分别为DREQ、HRQ、HLDA、DACK