己知正弦电流1的最大值(幅值〕Im为10A,频率f为50HZ,初相角ji为-60°口,求该电流的周期、频率、i的有效值符合下列选项()。〔提示=1.414〕
A. 0.01s,314rad/s,3.541A
B. 0.02s,314rad/s,7.1A
C. 0.02s,628rad/s,7.1A
D. 0.01s,628rad/s,3.541A
The davit launched life raft can be boarded().
A. from the water only
B. at the deck
C. by jumping down onto it
D. through the escape tube