问题
单项选择题
The establishment of INMARSAT as an independent organization marked a great step forward for maritime radio communications. What does “marked a great step” mean in the sentence?（）
A.To run faster than ever
B.To go forward
C.To march without stopping
D.A significant symbol of a great improvement in maritime communication
答案
参考答案：D
降压起动方式。假如全压起动时起动电压即为标称电压UN，起动电流为Iq，起动转矩为Tq。请按上述给定条件回答下列问题。