Take a look at the verb мочь/can:

Я и мечтать не могла об этом!

The Present tense

The Past tense

Vera also says:

Вы всё должны ^ увидеть своими глазами.

You already know modal verbs любить/to love и хотеть/to want from the Lesson 5. Now you have also learned a new modal verb мочь/can and a short adjective with a modal meaning должен/must.