Inside the computer, the operation system (of another software module called a data communication (71) )must decide which program will get control next. Each program remember, is associated (72) . a particular front -end port. If a program’s data have not yet reached its front - end buffer, there is no point giving that program control. Thus the data communication monitor sends its own (73) signal to the front -end devices next port is polled. Note that the (74) computer speed. The computer never has to wait for a terminal or a communication line. Instead, it is the expressive front - end processor that waits for the slower system (75) to respond.

（74）处填（）。

A．great

B．huge

C．mainframe

D．large

呼吸性碱中毒（）

A.pH7.30，PaCO₂64mmHg，BE+2mmol/L

B.pH7.20，PaCO₂70mmHg，EE-5mmol/L

C.pH7.45，PaCO₂60mmHg，BE+15mmol/L

D.pH7.48，PaCO₂30mmHg，BE-8mmol/L

E.pH7.38，PaCO₂54mmHg，BE-4mmol/L