We often talk about the weather. If we want to know about the weather, we can turn on the radio and   小题1:  the weather report. We can also turn on the TV and watch the Weather   小题2: . And we can ask other people in two different  小题3: , “What’s the weather like today?” or “How is the weather today?” You can also call at 96121 for the weather.

When it’s cold, we need to wear   小题4:  clothes. When it’s   小题5: , we need raincoats or umbrellas. When it’s hot, we need a cool place and a cold drink.

（）属于第三层VPN协议。

A．TCP

B．IPsec

C．PPOE

D．SSL