A.10V
B.7V
C.4V
D.2V
[单选题]A.B.C.D.
[单选题]A.74.25B.72.25C.95.26D.63.56
[单选题]A.19B.24C.29D.36
[单选题]A.原来的1/2倍和增大B.原来的1/2倍和减小C.减小和增大D.不变和不变