单项选择题 在ISO/OSI参考模型中,网络层的主要功能是A、提供可靠的端-端服务,透明地传送报文B、路由选择、拥塞控制与网络互连C、在通信实体之间传送以帧为单位的数据D、数据格式变换、数据加密与解密、数据压缩与恢复

单项选择题 （   ）是意识形态工作的主战场、最前沿。A. 电视B. 广播C. 报刊D. 互联网

单项选择题 关系型数据库是由众多二维表（基表）构成的，基表的列（字段）是基表的数据结构，一般情况下是固定不变的。

单项选择题 Fill in the blank with the most appropriate choice. The experimental investigation __________ that the addition of these fibers reduces the thermal conductivity of the composite specimen and yield a lightweight.

单项选择题 After a slow start, the plan soon took ______and was accepted by all.A.force boys to hide their emotions to be “real man”B.help to cultivate masculine aggressiveness in boys C.encourage boys to express their emotions more freelyD.naturally reinforce in boys that traditional image of a man