I just wamted to say that "to be +past participle" is the structure of the passive voice. The verb "to worry" can be used in passive structure too.
So we can say: He always worries about simple things.
We can also say: He always seems to be worried about simple things.(He is always worried about simple things.)
Humble, what I'm writing here isn't taken from M. Swan's or any other good grammar book. I'm writing my own grammar book which is a mixture of all good grammar books. I haven't published it yet.
