U盘的接口都采用（）接口。
A.UPS
B.USA
C.UBS
D.USB
参考答案：D
A．+→
B．→+
C．+→
D．→+
When should a project baseline be changed
A) When a major delay occurs.B) When an official change is made.C) When a cost increase occurs.D) Changes should never be made in the baseline.
+
→
→
+
+
→
→
+
