[Sync > Condvar](https://github.com/rust-lang/rust/blob/master/src/libstd/sync/condvar.rs#L38-L39) > The predicate is always verified inside of the mutex before determining that thread must block. Rather "determining that **a** thread"? [Alloc > Rc](https://github.com/rust-lang/rust/blob/master/src/liballoc/rc.rs#L15-L16) > The type `Rc<T>` provides shared ownership of a value of type `T`, allocated in the heap. Rather "allocated **on** the heap"? That's how it know it.