如故意投放危险物质，危害公共安全，尚未造成严重后果的，也构成了投放危险物质罪。
参考答案：对
Yuan Longping makes a great coutribution to _______ rice. We shoud learn ______ him. [ ]
A. growing; from
B. grow; about
C. grow; from
D. growing; to
如图中，定值电阻R1=2Ω，R2=3Ω，开关S断开和闭合时电流表的示数之比为______．
