镅-铍中子源是否放出中子和伽玛射线。
参考答案:对
--- I am going to visit the Shanghai EXPO this summer. Will you come with me?
---- Thanks. I’m afraid lots of people are planning for that. I prefer to stay at home rather than___ _ there.
A.go
B.went
C.to go
D.going
如图所示,小磁针静止不动,标出电源的正负极.