when do we use lets and when do we use let us, and what's the difference between them.
If you're making a suggestion, "let's" is the normal form.
what about " Let us " ?
Is it used to ask for permission ?
It is used more for suggestions than permission. For permission, you'd porbably add something like 'please let us'. Alone, it is used, but the contracted form is much more common. Here's a famous example of it:
http://www.bartleby.com/198/1.html
Here, the usage is fairly formal- 'let us go to the cinema' sounds a bit strained.![]()