、。
I consider him a wonderful teacher.
Literal
I [topic-は], him [object-を] wonderful teacher [quotative-だと] consider.
The pattern [object]を+[complement]だと+考える/思う is 'to consider/think of X as Y.' The だと combines the copula だ with the quotative と. ~ている form marks the considering as an ongoing state of opinion, not a single act of thought.