问题
单项选择题
SOLAS vessels should be able to communicate with a shore station（）.
A.no matter where they are and what time it is
B.at scheduled time and in major ocean regions
C.at fixed time and position
D.when they get permission
答案
参考答案：A
Pu的原子核静止在匀强磁场中．某时刻该原子核垂直于磁场方向放射出一个α粒子，变成铀的同位素，同时辐射出能量为E＝0.09 MeV的光子．已知钚原子核的质量M0＝238.999655 u，α粒子的质量m＝4.001509 u，反冲核的质量M＝234.993470 u．取1 u·c2＝931 MeV.