2. Only one train is permitted in each block at a time.
A: 正确
B: 错误
A: 正确
B: 错误
举一反三
- 2. Only one train is permitted in each block at a time.
- It is desired that the switch produce only one clock pulse(时钟脉冲) each time it is closed.
- 4.2Time Organization includes: 1. ______ time, do one event at a time; 2. ______ time, do many things at a time.
- Passengers are permitted ______ only one piece of hand luggage onto the plane.
- Niu Lang and Zhi Nǚ are permitted to meet each other only on the seventh day of the seventh month each year.