对于有消声要求的通风和空气调节系统，其风管内的风速( )。
A．需要恒定 B．越大越好 C．没有任何要求 D．越小越好
参考答案：D
_____ computer is the most important invention of _____ twentieth century. [ ]
A. A; the
B. The; the
C. The; 不填
D. A; 不填
If a lot of people say a film is not good, I won’t bother to see it, or I’ll wait _____ it comes out on DVD.
A.whether B. after C. though D. until
