题干
The man tried (尝试) several times (几次) to start the car, and he succeeded (成功）__________.
A：in the past
B：in the end
C：at first
D：at once
答案(点此获取答案解析）
B
The man tried (尝试) several times (几次) to start the car, and he succeeded (成功）__________.
A：in the past
B：in the end
C：at first
D：at once
是γ射线放射源，可用于农作物诱变育种，我国用该方法培育出了许多农作物新品种，对
