Incomplete Verbs.
Some verbs require other words to follow them, before they give full meaning. They are called Incomplete Verbs. Such are the verbs Be (am / is / are / ...), become, seem, look, appear, turn, grow …
Examples.
I am rather tired.
We were all over sixteen.
The weather has become much cooler.
He seems/looks very kind.
It appears to be true.
Our neighbours have turned quite unfriendly.
How tall you have grown!