— do you do your homework? —At 5: 00 p.m.[ ]
A. What time
B. What
C. Where
答案：A
A: How often do you exercise?
B: _____.
A. Less than two hours
B. Every day
C. Four times
D. Three to six hours
已知一通风管道，经仪器测得管内动压Hd=50mmH2O，静压Hj=70mmH2O，求管内全压Hq是多少？
