1. UNIT 13 Time Clauses

2. How do we show the time relationship between two sentences? We often use time words like: When Until Before After As / While Once

3. When Shows that one action happens immediately after another: When you click on a URL, your browser sends it to a DNS server When the DNS server finds the IP address, it sends it back to the browser

4. Once / After (+ Present Perfect) Its like when, but emphasizes that the first action has been completed: Once/After the DNS server has found the IP address, it sends it back to the browser Once/After the video has finished downloading, you can watch it

5. Until / Before They link an action and the limit of this action: The data packets are passed from router to router until/before they reach their destination The packets may travel by different routes until/before they reach the server

6. As / While They link two actions happening at the same time: As/While the individual packets reach the server, they are put back together As/While you watch the beginning of a video online, the rest of the video is downloading

7. Before / After + -ing Before and After can be followed by an –ing if the subject is the same in both sentences: The packets are passed from router to router before reaching their destination After finding the IP address, the DNS server sends it back to the browser

8. To sum up: When you click on a URL, your browser sends it to a DNS server (one action after another) Once/After the DNS server has found the IP address, it sends it back to the browser (first action completed) The data packets are passed from router to router until/before they reach their destination (time limit) As/While you watch the beginning of a video online, the rest of the video is downloading (two actions happening at the same time) The packets are passed from router to router before reaching their destination / After finding the IP address, the DNS server sends it back to the browser (before / after + -ing)