为了保证充分竞争，当投标人少于（）个时，应当重新招标。
A．6
B．5
C．4
D．3
参考答案：D
Throwable类有两个子类，分别是Error和______。
Computers have _____ many changes in the workplace. [ ]
A. heard about
B. known about
C. brought about
D. cared about
