单项选择题
Why can all the astronauts sleep at the same time（）
A．They have to follow the same timetable. B．The radio will take care of the aircraft for them. C．There are enough sleeping bags in the spacecraft. D．There is no need for them to watch over the spacecraft.
单项选择题 When the astronauts are working, sleeping bags are fastened（）
单项选择题 The proposal______, we'll have to make another decision about when to start the project.
单项选择题 ______to find the proper job, he decided to give up job-hunting in this city.
