A-A+
A．They built a much lighter rocket.B．They buil
问题详情
A．They built a much lighter rocket.
B．They built a much faster rocket.
C．They loaded the rocket with enough fuel.
D．They built a multistage rocket.
参考答案
正确答案：D
解析：在制造火箭推进器的过程中，科学家们意识到it would be difficult for one heavy rocket loaded with fuel to reach the moon，所以他们决定使用multistage rocket(多级火箭)。
