在北风天气航向150°的帆船甲看到左舷角30°乙船显示红、绿垂直两盏号灯和绿舷灯，且有碰撞危险，按国际避碰规则：（）

A.乙船一定右舷受风，甲船应给乙船让路；

B.乙船一定左舷受风，处于下风，且无法判断甲船哪舷受风，乙船应给甲船让路；

C.乙船左舷受风，甲船应给乙船让路；

D.无论乙船哪舷受风，甲船都应给乙船让路。

OSPF is a link-state routing protocol. It is designed to be run internal to a single (1) system. Each OSPF router maintains an identical(2) describing the autonomous system's topology. From this database, a routing table is calculated by constructing a shortest-path (3).OSPF recalculates routes quickly in the face of topological changes, utilizing aminimum of routing (4) traffic. OSPF provides support for equal-cost multipath. An area routing capability is provided, enabling.an additional level of routing protection and a reduction in routing protocol (5).

空白（1）处应选择（）

A.autonomous

B.network

C.computer

D.server