泥石流形成的基本条件有哪些？
参考答案：
形成泥石流必须具备有丰富的松散泥石物质来源，陡峻的山坡和较大的沟谷以及能大量集中水源的地形、地质和水文气象条件
典型投资者都是追求收益而又厌恶风险的。（）
If a DSC distress relay is transmitted from coast station , it will（）.
A.indicate the ship in distress that the alert has been received
B.alert ships in the area of a distress incident that a distress has occurred
C.inform other coast station of distress incident
D.repeat the distress alert in 5 minutes
