There are four connections since each connection transports exactly one request message and one response message. So, each object will have its one request message instead of there being only one request message.
It is because both of these web pages are on the same physical server (www.mit.edu).
In a nonpersistent connection, the connection closes after each connection. In this case, the connection will close once the first message is received, and there will be a new connection opened to send the second message.
The “Date:” is the time at which the request was created and not when the object was last modified.
Some HTTP response messages have an empty message body. For example, HTTP Status-Code of 204 and 304 MUST NOT include a message body. (RFC 2616)