(something) was supposed to (be / do something)

If you planned for something to happen one way, but in reality it happened another way, you can use "___ was supposed to ___." 

For example, imagine that you arranged a study group with some students at your university. One person didn't show up, so you write a text message to him:

You were supposed to meet us in front of the library at four.

This phrase appears in these lessons: